diff --git a/android/brave_java_sources.gni b/android/brave_java_sources.gni
index 09dda1a0eb8..c8f4500d335 100644
--- a/android/brave_java_sources.gni
+++ b/android/brave_java_sources.gni
@@ -535,7 +535,6 @@ brave_java_base_sources = [
   "//brave/android/java/org/chromium/base/BravePreferenceKeys.java",
   "//brave/android/java/org/chromium/base/BraveReflectionUtil.java",
   "//brave/android/java/org/chromium/base/BraveUrlConstants.java",
-  "//brave/android/java/org/chromium/base/Callbacks.java",
 ]
 
 brave_java_base_module_sources = [
diff --git a/android/java/org/chromium/base/Callbacks.java b/android/java/org/chromium/base/Callbacks.java
deleted file mode 100644
index 2f71242ee78..00000000000
--- a/android/java/org/chromium/base/Callbacks.java
+++ /dev/null
@@ -1,251 +0,0 @@
-/* Copyright (c) 2024 The Brave Authors. All rights reserved.
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-package org.chromium.base;
-
-import org.chromium.build.annotations.NullMarked;
-
-/** Contains a generic interface for callbacks. */
-@NullMarked
-public interface Callbacks {
-
-    /** A generic callback. */
-    interface Callback0 {
-        /** Call the callback. */
-        public void call();
-    }
-
-    /**
-     * A generic 1-argument callback.
-     *
-     * @param <T1> the type of argument 1.
-     */
-    interface Callback1<T1> {
-        /** Call the callback. */
-        public void call(T1 arg1);
-    }
-
-    /**
-     * A generic 2-argument callback.
-     *
-     * @param <T1> the type of argument 1.
-     * @param <T2> the type of argument 2.
-     */
-    interface Callback2<T1, T2> {
-        /** Call the callback. */
-        public void call(T1 arg1, T2 arg2);
-    }
-
-    /**
-     * A generic 3-argument callback.
-     *
-     * @param <T1> the type of argument 1.
-     * @param <T2> the type of argument 2.
-     * @param <T3> the type of argument 3.
-     */
-    interface Callback3<T1, T2, T3> {
-        /** Call the callback. */
-        public void call(T1 arg1, T2 arg2, T3 arg3);
-    }
-
-    /**
-     * A generic 4-argument callback.
-     *
-     * @param <T1> the type of argument 1.
-     * @param <T2> the type of argument 2.
-     * @param <T3> the type of argument 3.
-     * @param <T4> the type of argument 4.
-     */
-    interface Callback4<T1, T2, T3, T4> {
-        /** Call the callback. */
-        public void call(T1 arg1, T2 arg2, T3 arg3, T4 arg4);
-    }
-
-    /**
-     * A generic 5-argument callback.
-     *
-     * @param <T1> the type of argument 1.
-     * @param <T2> the type of argument 2.
-     * @param <T3> the type of argument 3.
-     * @param <T4> the type of argument 4.
-     * @param <T5> the type of argument 5.
-     */
-    interface Callback5<T1, T2, T3, T4, T5> {
-        /** Call the callback. */
-        public void call(T1 arg1, T2 arg2, T3 arg3, T4 arg4, T5 arg5);
-    }
-
-    /**
-     * A generic 6-argument callback.
-     *
-     * @param <T1> the type of argument 1.
-     * @param <T2> the type of argument 2.
-     * @param <T3> the type of argument 3.
-     * @param <T4> the type of argument 4.
-     * @param <T5> the type of argument 5.
-     * @param <T6> the type of argument 6.
-     */
-    interface Callback6<T1, T2, T3, T4, T5, T6> {
-        /** Call the callback. */
-        public void call(T1 arg1, T2 arg2, T3 arg3, T4 arg4, T5 arg5, T6 arg6);
-    }
-
-    /**
-     * A generic 7-argument callback.
-     *
-     * @param <T1> the type of argument 1.
-     * @param <T2> the type of argument 2.
-     * @param <T3> the type of argument 3.
-     * @param <T4> the type of argument 4.
-     * @param <T5> the type of argument 5.
-     * @param <T6> the type of argument 6.
-     * @param <T7> the type of argument 7.
-     */
-    interface Callback7<T1, T2, T3, T4, T5, T6, T7> {
-        /** Call the callback. */
-        public void call(T1 arg1, T2 arg2, T3 arg3, T4 arg4, T5 arg5, T6 arg6, T7 arg7);
-    }
-
-    /**
-     * A generic 11-argument callback.
-     *
-     * @param <T1> the type of argument 1.
-     * @param <T2> the type of argument 2.
-     * @param <T3> the type of argument 3.
-     * @param <T4> the type of argument 4.
-     * @param <T5> the type of argument 5.
-     * @param <T6> the type of argument 6.
-     * @param <T7> the type of argument 7.
-     * @param <T8> the type of argument 8.
-     * @param <T9> the type of argument 9.
-     * @param <T10> the type of argument 10.
-     * @param <T11> the type of argument 11.
-     */
-    interface Callback11<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11> {
-        /** Call the callback. */
-        public void call(
-                T1 arg1,
-                T2 arg2,
-                T3 arg3,
-                T4 arg4,
-                T5 arg5,
-                T6 arg6,
-                T7 arg7,
-                T8 arg8,
-                T9 arg9,
-                T10 arg10,
-                T11 arg11);
-    }
-
-    /**
-     * A generic 13-argument callback.
-     *
-     * @param <T1> the type of argument 1.
-     * @param <T2> the type of argument 2.
-     * @param <T3> the type of argument 3.
-     * @param <T4> the type of argument 4.
-     * @param <T5> the type of argument 5.
-     * @param <T6> the type of argument 6.
-     * @param <T7> the type of argument 7.
-     * @param <T8> the type of argument 8.
-     * @param <T9> the type of argument 9.
-     * @param <T10> the type of argument 10.
-     * @param <T11> the type of argument 11.
-     * @param <T12> the type of argument 12.
-     * @param <T13> the type of argument 13.
-     */
-    interface Callback13<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13> {
-        /** Call the callback. */
-        public void call(
-                T1 arg1,
-                T2 arg2,
-                T3 arg3,
-                T4 arg4,
-                T5 arg5,
-                T6 arg6,
-                T7 arg7,
-                T8 arg8,
-                T9 arg9,
-                T10 arg10,
-                T11 arg11,
-                T12 arg12,
-                T13 arg13);
-    }
-
-    /**
-     * A generic 22-argument callback.
-     *
-     * @param <T1> the type of argument 1.
-     * @param <T2> the type of argument 2.
-     * @param <T3> the type of argument 3.
-     * @param <T4> the type of argument 4.
-     * @param <T5> the type of argument 5.
-     * @param <T6> the type of argument 6.
-     * @param <T7> the type of argument 7.
-     * @param <T8> the type of argument 8.
-     * @param <T9> the type of argument 9.
-     * @param <T10> the type of argument 10.
-     * @param <T11> the type of argument 11.
-     * @param <T12> the type of argument 12.
-     * @param <T13> the type of argument 13.
-     * @param <T14> the type of argument 14.
-     * @param <T15> the type of argument 15.
-     * @param <T16> the type of argument 16.
-     * @param <T17> the type of argument 17.
-     * @param <T18> the type of argument 18.
-     * @param <T19> the type of argument 19.
-     * @param <T20> the type of argument 20.
-     * @param <T21> the type of argument 21.
-     * @param <T22> the type of argument 22.
-     */
-    interface Callback22<
-            T1,
-            T2,
-            T3,
-            T4,
-            T5,
-            T6,
-            T7,
-            T8,
-            T9,
-            T10,
-            T11,
-            T12,
-            T13,
-            T14,
-            T15,
-            T16,
-            T17,
-            T18,
-            T19,
-            T20,
-            T21,
-            T22> {
-        /** Call the callback. */
-        public void call(
-                T1 arg1,
-                T2 arg2,
-                T3 arg3,
-                T4 arg4,
-                T5 arg5,
-                T6 arg6,
-                T7 arg7,
-                T8 arg8,
-                T9 arg9,
-                T10 arg10,
-                T11 arg11,
-                T12 arg12,
-                T13 arg13,
-                T14 arg14,
-                T15 arg15,
-                T16 arg16,
-                T17 arg17,
-                T18 arg18,
-                T19 arg19,
-                T20 arg20,
-                T21 arg21,
-                T22 arg22);
-    }
-}
diff --git a/android/java/org/chromium/chrome/browser/app/domain/CryptoModel.java b/android/java/org/chromium/chrome/browser/app/domain/CryptoModel.java
index 4b33176c16c..82df768e27a 100644
--- a/android/java/org/chromium/chrome/browser/app/domain/CryptoModel.java
+++ b/android/java/org/chromium/chrome/browser/app/domain/CryptoModel.java
@@ -11,7 +11,6 @@ import androidx.annotation.NonNull;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
-import org.chromium.base.Callbacks.Callback1;
 import org.chromium.brave_wallet.mojom.AccountInfo;
 import org.chromium.brave_wallet.mojom.AssetRatioService;
 import org.chromium.brave_wallet.mojom.BlockchainRegistry;
@@ -43,6 +42,16 @@ import java.util.List;
 // - mAssetRatioService
 @SuppressWarnings("UnusedVariable")
 public class CryptoModel {
+    /**
+     * A generic 1-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     */
+    public interface Callback1<T1> {
+        /** Call the callback. */
+        void call(T1 arg1);
+    }
+
     private TxService mTxService;
     private final PendingTxHelper mPendingTxHelper;
     private KeyringService mKeyringService;
diff --git a/android/java/org/chromium/chrome/browser/app/domain/DappsModel.java b/android/java/org/chromium/chrome/browser/app/domain/DappsModel.java
index 1f7ce7c3b51..0586dcc4b97 100644
--- a/android/java/org/chromium/chrome/browser/app/domain/DappsModel.java
+++ b/android/java/org/chromium/chrome/browser/app/domain/DappsModel.java
@@ -8,7 +8,6 @@ package org.chromium.chrome.browser.app.domain;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
-import org.chromium.base.Callbacks;
 import org.chromium.brave_wallet.mojom.AccountInfo;
 import org.chromium.brave_wallet.mojom.BraveWalletService;
 import org.chromium.brave_wallet.mojom.CoinType;
@@ -33,6 +32,16 @@ import java.util.Collections;
 import java.util.List;
 
 public class DappsModel implements KeyringServiceObserver {
+    /**
+     * A generic 1-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     */
+    public interface Callback1<T1> {
+        /** Call the callback. */
+        void call(T1 arg1);
+    }
+
     private JsonRpcService mJsonRpcService;
     private final KeyringService mKeyringService;
     private BraveWalletService mBraveWalletService;
@@ -71,8 +80,9 @@ public class DappsModel implements KeyringServiceObserver {
         mKeyringService.addObserver(this);
     }
 
-    public void fetchAccountsForConnectionReq(@CoinType.EnumType int coinType,
-            Callbacks.Callback1<Pair<AccountInfo, List<AccountInfo>>> callback) {
+    public void fetchAccountsForConnectionReq(
+            @CoinType.EnumType int coinType,
+            Callback1<Pair<AccountInfo, List<AccountInfo>>> callback) {
         if (coinType != CoinType.ETH && coinType != CoinType.SOL) {
             callback.call(new Pair<>(null, Collections.emptyList()));
             return;
@@ -213,7 +223,7 @@ public class DappsModel implements KeyringServiceObserver {
         mBraveWalletService.notifySignMessageRequestProcessed(isApproved, id, null, error);
     }
 
-    public void getPendingSignMessageRequests(Callbacks.Callback1<SignMessageRequest[]> callback) {
+    public void getPendingSignMessageRequests(Callback1<SignMessageRequest[]> callback) {
         mBraveWalletService.getPendingSignMessageRequests(callback::call);
     }
 
diff --git a/android/java/org/chromium/chrome/browser/app/domain/KeyringModel.java b/android/java/org/chromium/chrome/browser/app/domain/KeyringModel.java
index 71ae86159ca..46e6b7a5c28 100644
--- a/android/java/org/chromium/chrome/browser/app/domain/KeyringModel.java
+++ b/android/java/org/chromium/chrome/browser/app/domain/KeyringModel.java
@@ -15,7 +15,6 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.Observer;
 
-import org.chromium.base.Callbacks;
 import org.chromium.base.Log;
 import org.chromium.brave_wallet.mojom.AccountInfo;
 import org.chromium.brave_wallet.mojom.AllAccountsInfo;
@@ -41,6 +40,16 @@ import java.util.Locale;
 import java.util.Set;
 
 public class KeyringModel implements KeyringServiceObserver {
+    /**
+     * A generic 1-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     */
+    public interface Callback1<T1> {
+        /** Call the callback. */
+        void call(T1 arg1);
+    }
+
     private static final String TAG = "KeyringModel";
     private final Object mLock = new Object();
 
@@ -119,8 +128,11 @@ public class KeyringModel implements KeyringServiceObserver {
         }
     }
 
-    public void getAccounts(Callbacks.Callback1<AccountInfo[]> callback1) {
-        mKeyringService.getAllAccounts(allAccounts -> { callback1.call(allAccounts.accounts); });
+    public void getAccounts(Callback1<AccountInfo[]> callback1) {
+        mKeyringService.getAllAccounts(
+                allAccounts -> {
+                    callback1.call(allAccounts.accounts);
+                });
     }
 
     public void isWalletCreated(@NonNull final KeyringService.IsWalletCreated_Response callback) {
@@ -135,7 +147,7 @@ public class KeyringModel implements KeyringServiceObserver {
             @CoinType.EnumType int coinType,
             @KeyringId.EnumType int keyringId,
             String accountName,
-            Callbacks.Callback1<Boolean> callback) {
+            Callback1<Boolean> callback) {
         mKeyringService.addAccount(
                 coinType,
                 keyringId,
@@ -149,7 +161,7 @@ public class KeyringModel implements KeyringServiceObserver {
             @CoinType.EnumType int coinType,
             String chainId,
             String accountName,
-            Callbacks.Callback1<Boolean> callback) {
+            Callback1<Boolean> callback) {
         @KeyringId.EnumType int keyringId = AssetUtils.getKeyring(coinType, chainId);
         if (accountName == null) {
             LiveDataUtil.observeOnce(
@@ -167,7 +179,7 @@ public class KeyringModel implements KeyringServiceObserver {
         }
     }
 
-    public void isWalletLocked(@NonNull final Callbacks.Callback1<Boolean> callback) {
+    public void isWalletLocked(@NonNull final Callback1<Boolean> callback) {
         mKeyringService.isLocked(callback::call);
     }
 
@@ -185,7 +197,7 @@ public class KeyringModel implements KeyringServiceObserver {
     }
 
     private void handleAddAccountResult(
-            AccountInfo result, @NonNull final Callbacks.Callback1<Boolean> callback) {
+            AccountInfo result, @NonNull final Callback1<Boolean> callback) {
         mCryptoSharedActions.updateCoinType();
         mCryptoSharedActions.onNewAccountAdded();
         callback.call(result != null);
@@ -216,7 +228,7 @@ public class KeyringModel implements KeyringServiceObserver {
             @NonNull final Set<NetworkInfo> availableNetworks,
             @NonNull final Set<NetworkInfo> selectedNetworks,
             @NonNull final JsonRpcService jsonRpcService,
-            @NonNull final Callbacks.Callback1<Boolean> callback) {
+            @NonNull final Callback1<Boolean> callback) {
         assertOnUiThread();
         generateWallet(
                 password,
@@ -250,7 +262,7 @@ public class KeyringModel implements KeyringServiceObserver {
             @NonNull final Set<NetworkInfo> availableNetworks,
             @NonNull final Set<NetworkInfo> selectedNetworks,
             @NonNull final JsonRpcService jsonRpcService,
-            @NonNull final Callbacks.Callback1<String> callback) {
+            @NonNull final Callback1<String> callback) {
         assertOnUiThread();
         generateWallet(
                 password,
@@ -270,8 +282,8 @@ public class KeyringModel implements KeyringServiceObserver {
             @NonNull final Set<NetworkInfo> availableNetworks,
             @NonNull final Set<NetworkInfo> selectedNetworks,
             @NonNull final JsonRpcService jsonRpcService,
-            @Nullable final Callbacks.Callback1<String> createCallback,
-            @Nullable final Callbacks.Callback1<Boolean> restoreCallback) {
+            @Nullable final Callback1<String> createCallback,
+            @Nullable final Callback1<Boolean> restoreCallback) {
         final Set<NetworkInfo> removeHiddenNetworks = new HashSet<>();
         final Set<NetworkInfo> addHiddenNetworks = new HashSet<>();
 
@@ -386,7 +398,7 @@ public class KeyringModel implements KeyringServiceObserver {
             @NonNull final String recoveryPhrase,
             final boolean legacyRestoreEnabled,
             @NonNull final Set<NetworkInfo> selectedNetworks,
-            @NonNull final Callbacks.Callback1<Boolean> callback) {
+            @NonNull final Callback1<Boolean> callback) {
         assertOnUiThread();
         mKeyringService.restoreWallet(
                 recoveryPhrase,
@@ -398,7 +410,7 @@ public class KeyringModel implements KeyringServiceObserver {
     private void finalizeWalletCreation(
             @NonNull final String password,
             @NonNull final Set<NetworkInfo> selectedNetworks,
-            @NonNull final Callbacks.Callback1<String> callback) {
+            @NonNull final Callback1<String> callback) {
         assertOnUiThread();
         mKeyringService.createWallet(
                 password,
@@ -408,7 +420,7 @@ public class KeyringModel implements KeyringServiceObserver {
     private <T> void createAccounts(
             final T result,
             @NonNull final Set<NetworkInfo> selectedNetworks,
-            @NonNull final Callbacks.Callback1<T> callback) {
+            @NonNull final Callback1<T> callback) {
         final Set<NetworkInfo> createAccounts = new HashSet<>();
 
         for (NetworkInfo networkInfo : selectedNetworks) {
@@ -455,8 +467,7 @@ public class KeyringModel implements KeyringServiceObserver {
         }
     }
 
-    private <T> void selectEthAccount(
-            final T result, @NonNull final Callbacks.Callback1<T> callback) {
+    private <T> void selectEthAccount(final T result, @NonNull final Callback1<T> callback) {
         mKeyringService.getAllAccounts(
                 allAccounts -> {
                     if (allAccounts.ethDappSelectedAccount != null) {
diff --git a/android/java/org/chromium/chrome/browser/app/domain/NetworkModel.java b/android/java/org/chromium/chrome/browser/app/domain/NetworkModel.java
index 5a6fd041a86..32f441de3e6 100644
--- a/android/java/org/chromium/chrome/browser/app/domain/NetworkModel.java
+++ b/android/java/org/chromium/chrome/browser/app/domain/NetworkModel.java
@@ -13,7 +13,6 @@ import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MediatorLiveData;
 import androidx.lifecycle.MutableLiveData;
 
-import org.chromium.base.Callbacks;
 import org.chromium.brave_wallet.mojom.AccountInfo;
 import org.chromium.brave_wallet.mojom.BraveWalletConstants;
 import org.chromium.brave_wallet.mojom.BraveWalletService;
@@ -36,25 +35,35 @@ import java.util.Map;
 import java.util.stream.Collectors;
 
 public class NetworkModel implements JsonRpcServiceObserver {
+    /**
+     * A generic 1-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     */
+    public interface Callback1<T1> {
+        /** Call the callback. */
+        void call(T1 arg1);
+    }
+
     private BraveWalletService mBraveWalletService;
     private JsonRpcService mJsonRpcService;
     private final Object mLock = new Object();
     private Mode mMode = Mode.WALLET_MODE;
 
-    private final MediatorLiveData<String> _mChainId;
-    private final MediatorLiveData<List<NetworkInfo>> _mDefaultCoinCryptoNetworks;
-    private final MutableLiveData<List<NetworkInfo>> _mCryptoNetworks;
+    private final MediatorLiveData<String> mMediatorChainId;
+    private final MediatorLiveData<List<NetworkInfo>> mMediatorDefaultCoinCryptoNetworks;
+    private final MutableLiveData<List<NetworkInfo>> mMutableCryptoNetworks;
     private final CryptoSharedData mSharedData;
     private final CryptoSharedActions mCryptoActions;
-    private final MediatorLiveData<Pair<String, List<NetworkInfo>>> _mPairChainAndNetwork;
-    private final MediatorLiveData<NetworkInfo> _mNeedToCreateAccountForNetwork;
-    private final MediatorLiveData<NetworkInfo> _mDefaultNetwork;
-    private final MediatorLiveData<String[]> _mCustomNetworkIds;
-    private final MediatorLiveData<List<NetworkInfo>> _mPrimaryNetworks;
-    private final MediatorLiveData<List<NetworkInfo>> _mSecondaryNetworks;
+    private final MediatorLiveData<Pair<String, List<NetworkInfo>>> mMediatorPairChainAndNetwork;
+    private final MediatorLiveData<NetworkInfo> mMediatorNeedToCreateAccountForNetwork;
+    private final MediatorLiveData<NetworkInfo> mMediatorDefaultNetwork;
+    private final MediatorLiveData<String[]> mMediatorCustomNetworkIds;
+    private final MediatorLiveData<List<NetworkInfo>> mMediatorPrimaryNetworks;
+    private final MediatorLiveData<List<NetworkInfo>> mMediatorSecondaryNetworks;
 
     public final LiveData<String> mChainId;
-    private final MutableLiveData<NetworkLists> _mNetworkLists;
+    private final MutableLiveData<NetworkLists> mMutableNetworkLists;
     public final LiveData<String[]> mCustomNetworkIds;
     public LiveData<NetworkInfo> mNeedToCreateAccountForNetwork;
     public final LiveData<Pair<String, List<NetworkInfo>>> mPairChainAndNetwork;
@@ -76,62 +85,63 @@ public class NetworkModel implements JsonRpcServiceObserver {
         mSharedData = sharedData;
         mCryptoActions = cryptoSharedActions;
 
-        _mChainId = new MediatorLiveData<>();
-        _mChainId.setValue(BraveWalletConstants.MAINNET_CHAIN_ID);
-        mChainId = _mChainId;
-        _mDefaultCoinCryptoNetworks = new MediatorLiveData<>();
-        mDefaultCoinCryptoNetworks = _mDefaultCoinCryptoNetworks;
-        _mCryptoNetworks = new MutableLiveData<>(Collections.emptyList());
-        mCryptoNetworks = _mCryptoNetworks;
-        _mPairChainAndNetwork = new MediatorLiveData<>();
-        mPairChainAndNetwork = _mPairChainAndNetwork;
-        _mDefaultNetwork = new MediatorLiveData<>();
-        mDefaultNetwork = _mDefaultNetwork;
-        _mNeedToCreateAccountForNetwork = new MediatorLiveData<>();
-        mNeedToCreateAccountForNetwork = _mNeedToCreateAccountForNetwork;
-        _mCustomNetworkIds = new MediatorLiveData<>();
-        _mCustomNetworkIds.postValue(new String[0]);
-        mCustomNetworkIds = _mCustomNetworkIds;
-        _mPrimaryNetworks = new MediatorLiveData<>();
-        mPrimaryNetworks = _mPrimaryNetworks;
-        _mSecondaryNetworks = new MediatorLiveData<>();
-        mSecondaryNetworks = _mSecondaryNetworks;
+        mMediatorChainId = new MediatorLiveData<>();
+        mMediatorChainId.setValue(BraveWalletConstants.MAINNET_CHAIN_ID);
+        mChainId = mMediatorChainId;
+        mMediatorDefaultCoinCryptoNetworks = new MediatorLiveData<>();
+        mDefaultCoinCryptoNetworks = mMediatorDefaultCoinCryptoNetworks;
+        mMutableCryptoNetworks = new MutableLiveData<>(Collections.emptyList());
+        mCryptoNetworks = mMutableCryptoNetworks;
+        mMediatorPairChainAndNetwork = new MediatorLiveData<>();
+        mPairChainAndNetwork = mMediatorPairChainAndNetwork;
+        mMediatorDefaultNetwork = new MediatorLiveData<>();
+        mDefaultNetwork = mMediatorDefaultNetwork;
+        mMediatorNeedToCreateAccountForNetwork = new MediatorLiveData<>();
+        mNeedToCreateAccountForNetwork = mMediatorNeedToCreateAccountForNetwork;
+        mMediatorCustomNetworkIds = new MediatorLiveData<>();
+        mMediatorCustomNetworkIds.postValue(new String[0]);
+        mCustomNetworkIds = mMediatorCustomNetworkIds;
+        mMediatorPrimaryNetworks = new MediatorLiveData<>();
+        mPrimaryNetworks = mMediatorPrimaryNetworks;
+        mMediatorSecondaryNetworks = new MediatorLiveData<>();
+        mSecondaryNetworks = mMediatorSecondaryNetworks;
         jsonRpcService.addObserver(this);
-        _mNetworkLists = new MutableLiveData<>();
-        mNetworkLists = _mNetworkLists;
-        _mPairChainAndNetwork.setValue(Pair.create("", Collections.emptyList()));
-        _mPairChainAndNetwork.addSource(
-                _mChainId,
+        mMutableNetworkLists = new MutableLiveData<>();
+        mNetworkLists = mMutableNetworkLists;
+        mMediatorPairChainAndNetwork.setValue(Pair.create("", Collections.emptyList()));
+        mMediatorPairChainAndNetwork.addSource(
+                mMediatorChainId,
                 chainId -> {
-                    _mPairChainAndNetwork.setValue(
-                            Pair.create(chainId, _mDefaultCoinCryptoNetworks.getValue()));
+                    mMediatorPairChainAndNetwork.setValue(
+                            Pair.create(chainId, mMediatorDefaultCoinCryptoNetworks.getValue()));
                 });
-        _mPairChainAndNetwork.addSource(
-                _mDefaultCoinCryptoNetworks,
+        mMediatorPairChainAndNetwork.addSource(
+                mMediatorDefaultCoinCryptoNetworks,
                 networks -> {
-                    _mPairChainAndNetwork.setValue(Pair.create(_mChainId.getValue(), networks));
+                    mMediatorPairChainAndNetwork.setValue(
+                            Pair.create(mMediatorChainId.getValue(), networks));
                 });
-        _mDefaultNetwork.addSource(
-                _mPairChainAndNetwork,
+        mMediatorDefaultNetwork.addSource(
+                mMediatorPairChainAndNetwork,
                 chainIdAndInfosPair -> {
                     String chainId = chainIdAndInfosPair.first;
                     List<NetworkInfo> cryptoNetworks = chainIdAndInfosPair.second;
                     if (chainId == null || cryptoNetworks == null) return;
                     for (NetworkInfo networkInfo : cryptoNetworks) {
                         if (networkInfo.chainId.equals(chainId)) {
-                            _mDefaultNetwork.postValue(networkInfo);
+                            mMediatorDefaultNetwork.postValue(networkInfo);
                             break;
                         }
                     }
                 });
-        _mChainId.addSource(mSharedData.getCoinTypeLd(), coinType -> updateChainId());
-        _mDefaultCoinCryptoNetworks.addSource(
+        mMediatorChainId.addSource(mSharedData.getCoinTypeLd(), coinType -> updateChainId());
+        mMediatorDefaultCoinCryptoNetworks.addSource(
                 mSharedData.getCoinTypeLd(),
                 coinType -> {
                     getAllNetworks(
                             mJsonRpcService,
                             networkInfoSet -> {
-                                _mDefaultCoinCryptoNetworks.postValue(
+                                mMediatorDefaultCoinCryptoNetworks.postValue(
                                         new ArrayList<>(
                                                 networkInfoSet.stream()
                                                         .filter(n -> n.coin == coinType)
@@ -139,30 +149,38 @@ public class NetworkModel implements JsonRpcServiceObserver {
                             });
                 });
 
-        _mCustomNetworkIds.addSource(
+        mMediatorCustomNetworkIds.addSource(
                 mSharedData.getCoinTypeLd(),
                 coinType -> {
-                    mJsonRpcService.getCustomNetworks(coinType, _mCustomNetworkIds::postValue);
+                    mJsonRpcService.getCustomNetworks(
+                            coinType, mMediatorCustomNetworkIds::postValue);
+                });
+        mMediatorPrimaryNetworks.addSource(
+                mCryptoNetworks,
+                networkInfos -> {
+                    List<NetworkInfo> primaryNws = new ArrayList<>();
+                    for (NetworkInfo networkInfo : networkInfos) {
+                        if (WalletConstants.SUPPORTED_TOP_LEVEL_CHAIN_IDS.contains(
+                                networkInfo.chainId)) {
+                            primaryNws.add(networkInfo);
+                        }
+                    }
+                    mMediatorPrimaryNetworks.postValue(primaryNws);
+                });
+        mMediatorSecondaryNetworks.addSource(
+                mCryptoNetworks,
+                networkInfos -> {
+                    List<NetworkInfo> secondaryNws = new ArrayList<>();
+                    for (NetworkInfo networkInfo : networkInfos) {
+                        if (!WalletConstants.SUPPORTED_TOP_LEVEL_CHAIN_IDS.contains(
+                                        networkInfo.chainId)
+                                && !WalletConstants.KNOWN_TEST_CHAIN_IDS.contains(
+                                        networkInfo.chainId)) {
+                            secondaryNws.add(networkInfo);
+                        }
+                    }
+                    mMediatorSecondaryNetworks.postValue(secondaryNws);
                 });
-        _mPrimaryNetworks.addSource(mCryptoNetworks, networkInfos -> {
-            List<NetworkInfo> primaryNws = new ArrayList<>();
-            for (NetworkInfo networkInfo : networkInfos) {
-                if (WalletConstants.SUPPORTED_TOP_LEVEL_CHAIN_IDS.contains(networkInfo.chainId)) {
-                    primaryNws.add(networkInfo);
-                }
-            }
-            _mPrimaryNetworks.postValue(primaryNws);
-        });
-        _mSecondaryNetworks.addSource(mCryptoNetworks, networkInfos -> {
-            List<NetworkInfo> secondaryNws = new ArrayList<>();
-            for (NetworkInfo networkInfo : networkInfos) {
-                if (!WalletConstants.SUPPORTED_TOP_LEVEL_CHAIN_IDS.contains(networkInfo.chainId)
-                        && !WalletConstants.KNOWN_TEST_CHAIN_IDS.contains(networkInfo.chainId)) {
-                    secondaryNws.add(networkInfo);
-                }
-            }
-            _mSecondaryNetworks.postValue(secondaryNws);
-        });
     }
 
     private void updateChainId() {
@@ -178,20 +196,24 @@ public class NetworkModel implements JsonRpcServiceObserver {
                 return;
             }
             @CoinType.EnumType int coin = coinBoxed;
-            mJsonRpcService.getNetwork(coin, null, networkInfo -> {
-                if (networkInfo != null) {
-                    _mChainId.postValue(networkInfo.chainId);
-                }
-            });
+            mJsonRpcService.getNetwork(
+                    coin,
+                    null,
+                    networkInfo -> {
+                        if (networkInfo != null) {
+                            mMediatorChainId.postValue(networkInfo.chainId);
+                        }
+                    });
         } else if (mMode == Mode.PANEL_MODE) {
             if (mBraveWalletService == null) {
                 return;
             }
-            mBraveWalletService.getNetworkForSelectedAccountOnActiveOrigin(networkInfo -> {
-                if (networkInfo != null) {
-                    _mChainId.postValue(networkInfo.chainId);
-                }
-            });
+            mBraveWalletService.getNetworkForSelectedAccountOnActiveOrigin(
+                    networkInfo -> {
+                        if (networkInfo != null) {
+                            mMediatorChainId.postValue(networkInfo.chainId);
+                        }
+                    });
         }
     }
 
@@ -202,18 +224,21 @@ public class NetworkModel implements JsonRpcServiceObserver {
 
     void setUpAccountObserver(LiveData<List<AccountInfo>> accounts) {
         // getAccounts can be null as it's being set via a setter
-        // clear the _mNeedToCreateAccountForNetwork state once a account has been created
+        // clear the mMediatorNeedToCreateAccountForNetwork state once a account has been created
         // think we may not need this since it's being cleared with clearCreateAccountState anyway
         if (mSharedData.getAccounts() == null) return;
-        _mNeedToCreateAccountForNetwork.addSource(accounts, accountInfos -> {
-            if (_mNeedToCreateAccountForNetwork.getValue() == null) return;
-            for (AccountInfo accountInfo : accountInfos) {
-                if (accountInfo.accountId.coin == _mNeedToCreateAccountForNetwork.getValue().coin) {
-                    _mNeedToCreateAccountForNetwork.postValue(null);
-                    break;
-                }
-            }
-        });
+        mMediatorNeedToCreateAccountForNetwork.addSource(
+                accounts,
+                accountInfos -> {
+                    if (mMediatorNeedToCreateAccountForNetwork.getValue() == null) return;
+                    for (AccountInfo accountInfo : accountInfos) {
+                        if (accountInfo.accountId.coin
+                                == mMediatorNeedToCreateAccountForNetwork.getValue().coin) {
+                            mMediatorNeedToCreateAccountForNetwork.postValue(null);
+                            break;
+                        }
+                    }
+                });
     }
 
     public void resetServices(
@@ -231,7 +256,7 @@ public class NetworkModel implements JsonRpcServiceObserver {
 
     @SuppressWarnings("NoStreams")
     static void getAllNetworks(
-            JsonRpcService jsonRpcService, Callbacks.Callback1<List<NetworkInfo>> callback) {
+            JsonRpcService jsonRpcService, Callback1<List<NetworkInfo>> callback) {
         if (jsonRpcService == null) {
             callback.call(Collections.emptyList());
             return;
@@ -278,7 +303,7 @@ public class NetworkModel implements JsonRpcServiceObserver {
             getAllNetworks(
                     mJsonRpcService,
                     cryptoNetworks -> {
-                        _mCryptoNetworks.postValue(cryptoNetworks);
+                        mMutableCryptoNetworks.postValue(cryptoNetworks);
 
                         List<NetworkInfo> primary = new ArrayList<>();
                         List<NetworkInfo> secondary = new ArrayList<>();
@@ -295,20 +320,24 @@ public class NetworkModel implements JsonRpcServiceObserver {
                                 secondary.add(networkInfo);
                             }
                         }
-                        _mNetworkLists.postValue(networkLists);
+                        mMutableNetworkLists.postValue(networkLists);
                     });
         }
     }
 
-    public void setNetworkWithAccountCheck(NetworkInfo networkToBeSetAsSelected,
-            boolean setNetworkAsDefault, Callbacks.Callback1<Boolean> callback) {
-        NetworkInfo selectedNetwork = _mDefaultNetwork.getValue();
+    public void setNetworkWithAccountCheck(
+            NetworkInfo networkToBeSetAsSelected,
+            boolean setNetworkAsDefault,
+            Callback1<Boolean> callback) {
+        NetworkInfo selectedNetwork = mMediatorDefaultNetwork.getValue();
         if (isSameNetwork(networkToBeSetAsSelected, selectedNetwork)) return;
 
         mBraveWalletService.ensureSelectedAccountForChain(
-                networkToBeSetAsSelected.coin, networkToBeSetAsSelected.chainId, accountId -> {
+                networkToBeSetAsSelected.coin,
+                networkToBeSetAsSelected.chainId,
+                accountId -> {
                     if (accountId == null) {
-                        _mNeedToCreateAccountForNetwork.postValue(networkToBeSetAsSelected);
+                        mMediatorNeedToCreateAccountForNetwork.postValue(networkToBeSetAsSelected);
                         callback.call(false);
                         return;
                     }
@@ -322,9 +351,10 @@ public class NetworkModel implements JsonRpcServiceObserver {
     }
 
     public void setNetworkForSelectedAccountOnActiveOrigin(
-            NetworkInfo networkToBeSetAsSelected, Callbacks.Callback1<Boolean> callback) {
+            NetworkInfo networkToBeSetAsSelected, Callback1<Boolean> callback) {
         mBraveWalletService.setNetworkForSelectedAccountOnActiveOrigin(
-                networkToBeSetAsSelected.chainId, success -> {
+                networkToBeSetAsSelected.chainId,
+                success -> {
                     callback.call(success);
                     mCryptoActions.updateCoinType();
                     init();
@@ -332,8 +362,7 @@ public class NetworkModel implements JsonRpcServiceObserver {
     }
 
     public void setDefaultNetwork(
-            @NonNull final NetworkInfo networkInfo,
-            @NonNull final Callbacks.Callback1<Boolean> callback) {
+            @NonNull final NetworkInfo networkInfo, @NonNull final Callback1<Boolean> callback) {
         mJsonRpcService.setNetwork(
                 networkInfo.chainId,
                 networkInfo.coin,
@@ -346,12 +375,12 @@ public class NetworkModel implements JsonRpcServiceObserver {
     }
 
     public void clearCreateAccountState() {
-        _mNeedToCreateAccountForNetwork.postValue(null);
+        mMediatorNeedToCreateAccountForNetwork.postValue(null);
     }
 
     public NetworkInfo getNetwork(String chainId) {
         if (TextUtils.isEmpty(chainId)) return null;
-        List<NetworkInfo> cryptoNws = JavaUtils.safeVal(_mCryptoNetworks.getValue());
+        List<NetworkInfo> cryptoNws = JavaUtils.safeVal(mMutableCryptoNetworks.getValue());
         for (NetworkInfo info : cryptoNws) {
             if (info.chainId.equals(chainId)) {
                 return info;
diff --git a/android/java/org/chromium/chrome/browser/app/helpers/ImageLoader.java b/android/java/org/chromium/chrome/browser/app/helpers/ImageLoader.java
index 358ea7de46a..5d59de2b467 100644
--- a/android/java/org/chromium/chrome/browser/app/helpers/ImageLoader.java
+++ b/android/java/org/chromium/chrome/browser/app/helpers/ImageLoader.java
@@ -38,7 +38,6 @@ import org.xmlpull.v1.XmlPullParserException;
 import org.xmlpull.v1.XmlPullParserFactory;
 import org.xmlpull.v1.XmlSerializer;
 
-import org.chromium.base.Callbacks;
 import org.chromium.base.ContextUtils;
 import org.chromium.chrome.browser.app.BraveActivity;
 import org.chromium.chrome.browser.content.WebContentsFactory;
@@ -430,11 +429,21 @@ public class ImageLoader {
         return url.endsWith(".gif") || url.endsWith("=gif");
     }
 
+    /**
+     * A generic 1-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     */
+    public interface Callback1<T1> {
+        /** Call the callback. */
+        void call(T1 arg1);
+    }
+
     public static void fetchFavIcon(
             String originSpecUrl,
             boolean useIncognitoNtpIcon,
             WeakReference<Context> context,
-            Callbacks.Callback1<Bitmap> callback) {
+            Callback1<Bitmap> callback) {
         try {
             BraveActivity activity = BraveActivity.getBraveActivity();
             FaviconHelper.FaviconImageCallback imageCallback =
diff --git a/android/java/org/chromium/chrome/browser/crypto_wallet/BraveWalletProviderDelegateImplHelper.java b/android/java/org/chromium/chrome/browser/crypto_wallet/BraveWalletProviderDelegateImplHelper.java
index 479f96aaacf..4412b1f7c7e 100644
--- a/android/java/org/chromium/chrome/browser/crypto_wallet/BraveWalletProviderDelegateImplHelper.java
+++ b/android/java/org/chromium/chrome/browser/crypto_wallet/BraveWalletProviderDelegateImplHelper.java
@@ -10,18 +10,26 @@ import org.jni_zero.JNINamespace;
 import org.jni_zero.NativeMethods;
 
 import org.chromium.base.Callback;
-import org.chromium.base.Callbacks;
 import org.chromium.base.Log;
 import org.chromium.brave_wallet.mojom.CoinType;
 import org.chromium.chrome.browser.app.BraveActivity;
 import org.chromium.chrome.browser.settings.BraveWalletPreferences;
 import org.chromium.content_public.browser.WebContents;
 
-/**
- * @noinspection unused
- */
+/** Helper class for BraveWalletProviderDelegate implementation. */
 @JNINamespace("brave_wallet")
+@SuppressWarnings("unused")
 public class BraveWalletProviderDelegateImplHelper {
+    /**
+     * A generic 1-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     */
+    public interface Callback1<T1> {
+        /** Call the callback. */
+        void call(T1 arg1);
+    }
+
     private static final String TAG = "BraveWalletProvider";
 
     @CalledByNative
@@ -90,7 +98,7 @@ public class BraveWalletProviderDelegateImplHelper {
     }
 
     public static void isSolanaConnected(
-            WebContents webContents, String account, Callbacks.Callback1<Boolean> callback) {
+            WebContents webContents, String account, Callback1<Boolean> callback) {
         Callback<Boolean> callbackWrapper =
                 result -> {
                     callback.call(result);
diff --git a/android/java/org/chromium/chrome/browser/crypto_wallet/adapters/TwoLineItemRecyclerViewAdapter.java b/android/java/org/chromium/chrome/browser/crypto_wallet/adapters/TwoLineItemRecyclerViewAdapter.java
index b07cb96cbe2..807cfb39ca0 100644
--- a/android/java/org/chromium/chrome/browser/crypto_wallet/adapters/TwoLineItemRecyclerViewAdapter.java
+++ b/android/java/org/chromium/chrome/browser/crypto_wallet/adapters/TwoLineItemRecyclerViewAdapter.java
@@ -17,7 +17,6 @@ import android.widget.TextView;
 import androidx.annotation.NonNull;
 import androidx.recyclerview.widget.RecyclerView;
 
-import org.chromium.base.Callbacks;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.crypto_wallet.util.AndroidUtils;
 import org.chromium.chrome.browser.crypto_wallet.util.Utils;
@@ -28,6 +27,27 @@ import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 
 public class TwoLineItemRecyclerViewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
+    /**
+     * A generic 1-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     */
+    public interface Callback1<T1> {
+        /** Call the callback. */
+        void call(T1 arg1);
+    }
+
+    /**
+     * A generic 2-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     * @param <T2> The type of the second argument.
+     */
+    public interface Callback2<T1, T2> {
+        /** Call the callback. */
+        void call(T1 arg1, T2 arg2);
+    }
+
     private List<TwoLineItem> mValues;
     private final ExecutorService mExecutor;
     private final Handler mHandler;
@@ -199,12 +219,10 @@ public class TwoLineItemRecyclerViewAdapter extends RecyclerView.Adapter<Recycle
         public ImageType imageType;
         public String imgData;
 
-        public Callbacks.Callback2<TextView, TextView> updateViewCb;
+        public Callback2<TextView, TextView> updateViewCb;
 
         public TwoLineItemText(
-                String title,
-                String subTitle,
-                Callbacks.Callback2<TextView, TextView> customUiChanges) {
+                String title, String subTitle, Callback2<TextView, TextView> customUiChanges) {
             this(title, subTitle);
             this.updateViewCb = customUiChanges;
         }
@@ -250,7 +268,7 @@ public class TwoLineItemRecyclerViewAdapter extends RecyclerView.Adapter<Recycle
 
     public static class TwoLineSingleText implements TwoLineItem {
         public String mText;
-        public Callbacks.Callback1<TextView> updateViewCb;
+        public Callback1<TextView> updateViewCb;
 
         public TwoLineSingleText() {
             mText = "";
diff --git a/android/java/org/chromium/chrome/browser/crypto_wallet/util/AssetsPricesHelper.java b/android/java/org/chromium/chrome/browser/crypto_wallet/util/AssetsPricesHelper.java
index f00720559df..9345b3421a7 100644
--- a/android/java/org/chromium/chrome/browser/crypto_wallet/util/AssetsPricesHelper.java
+++ b/android/java/org/chromium/chrome/browser/crypto_wallet/util/AssetsPricesHelper.java
@@ -5,7 +5,6 @@
 
 package org.chromium.chrome.browser.crypto_wallet.util;
 
-import org.chromium.base.Callbacks;
 import org.chromium.base.Log;
 import org.chromium.brave_wallet.mojom.AssetPrice;
 import org.chromium.brave_wallet.mojom.AssetPriceRequest;
@@ -23,7 +22,7 @@ public class AssetsPricesHelper {
     public static void fetchPrices(
             AssetRatioService assetRatioService,
             BlockchainToken[] assets,
-            Callbacks.Callback1<List<AssetPrice>> callback) {
+            AsyncUtils.Callback1<List<AssetPrice>> callback) {
         List<AssetPriceRequest> requests = new ArrayList<>();
 
         for (BlockchainToken asset : assets) {
diff --git a/android/java/org/chromium/chrome/browser/crypto_wallet/util/AsyncUtils.java b/android/java/org/chromium/chrome/browser/crypto_wallet/util/AsyncUtils.java
index 610d8ce55ff..680f1b7ab5e 100644
--- a/android/java/org/chromium/chrome/browser/crypto_wallet/util/AsyncUtils.java
+++ b/android/java/org/chromium/chrome/browser/crypto_wallet/util/AsyncUtils.java
@@ -7,7 +7,6 @@ package org.chromium.chrome.browser.crypto_wallet.util;
 
 import static org.chromium.chrome.browser.crypto_wallet.util.Utils.warnWhenError;
 
-import org.chromium.base.Callbacks;
 import org.chromium.brave_wallet.mojom.AssetPrice;
 import org.chromium.brave_wallet.mojom.AssetRatioService;
 import org.chromium.brave_wallet.mojom.AssetTimePrice;
@@ -28,6 +27,40 @@ import java.util.List;
 public class AsyncUtils {
     private static final String TAG = "AsyncUtils";
 
+    /**
+     * A generic 1-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     */
+    public interface Callback1<T1> {
+        /** Call the callback. */
+        void call(T1 arg1);
+    }
+
+    /**
+     * A generic 2-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     * @param <T2> The type of the second argument.
+     */
+    public interface Callback2<T1, T2> {
+        /** Call the callback. */
+        void call(T1 arg1, T2 arg2);
+    }
+
+    /**
+     * A generic 4-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     * @param <T2> The type of the second argument.
+     * @param <T3> The type of the third argument.
+     * @param <T4> The type of the fourth argument.
+     */
+    public interface Callback4<T1, T2, T3, T4> {
+        /** Call the callback. */
+        void call(T1 arg1, T2 arg2, T3 arg3, T4 arg4);
+    }
+
     // Helper to track multiple wallet services responses
     public static class MultiResponseHandler {
         private Runnable mWhenAllCompletedRunnable;
@@ -243,7 +276,7 @@ public class AsyncUtils {
     }
 
     public static class FetchPricesResponseContext extends SingleResponseBaseContext
-            implements Callbacks.Callback1<List<AssetPrice>> {
+            implements Callback1<List<AssetPrice>> {
         public List<AssetPrice> assetPrices;
 
         public FetchPricesResponseContext(Runnable responseCompleteCallback) {
@@ -258,7 +291,7 @@ public class AsyncUtils {
     }
 
     public static class GetNativeAssetsBalancesResponseContext extends SingleResponseBaseContext
-            implements Callbacks.Callback2<Integer, HashMap<String, Double>> {
+            implements Callback2<Integer, HashMap<String, Double>> {
         public int coinType;
         public HashMap<String, Double> nativeAssetsBalances;
 
@@ -275,7 +308,7 @@ public class AsyncUtils {
     }
 
     public static class GetBlockchainTokensBalancesResponseContext extends SingleResponseBaseContext
-            implements Callbacks.Callback2<Integer, HashMap<String, HashMap<String, Double>>> {
+            implements Callback2<Integer, HashMap<String, HashMap<String, Double>>> {
         public HashMap<String, HashMap<String, Double>> blockchainTokensBalances;
         public int coinType;
 
@@ -294,7 +327,7 @@ public class AsyncUtils {
     }
 
     public static class GetTxExtraInfoResponseContext extends SingleResponseBaseContext
-            implements Callbacks.Callback4<
+            implements Callback4<
                     List<AssetPrice>,
                     BlockchainToken[],
                     HashMap<String, Double>,
@@ -346,7 +379,7 @@ public class AsyncUtils {
     }
 
     public static class GetP3ABalancesContext extends SingleResponseBaseContext
-            implements Callbacks.Callback1<HashMap<Integer, HashSet<String>>> {
+            implements Callback1<HashMap<Integer, HashSet<String>>> {
         public HashMap<Integer, HashSet<String>> activeAddresses;
 
         public GetP3ABalancesContext(Runnable responseCompleteCallback) {
diff --git a/android/java/org/chromium/chrome/browser/crypto_wallet/util/BalanceHelper.java b/android/java/org/chromium/chrome/browser/crypto_wallet/util/BalanceHelper.java
index 040b0e6a0a2..0a4d0d470b6 100644
--- a/android/java/org/chromium/chrome/browser/crypto_wallet/util/BalanceHelper.java
+++ b/android/java/org/chromium/chrome/browser/crypto_wallet/util/BalanceHelper.java
@@ -7,7 +7,6 @@ package org.chromium.chrome.browser.crypto_wallet.util;
 
 import androidx.annotation.NonNull;
 
-import org.chromium.base.Callbacks;
 import org.chromium.brave_wallet.mojom.AccountInfo;
 import org.chromium.brave_wallet.mojom.BlockchainRegistry;
 import org.chromium.brave_wallet.mojom.BlockchainToken;
@@ -44,7 +43,7 @@ public class BalanceHelper {
             @NonNull final JsonRpcService jsonRpcService,
             @NonNull final NetworkInfo selectedNetwork,
             @NonNull final AccountInfo[] accounts,
-            @NonNull final Callbacks.Callback2<Integer, HashMap<String, Double>> callback) {
+            @NonNull final AsyncUtils.Callback2<Integer, HashMap<String, Double>> callback) {
         HashMap<String, Double> nativeAssetsBalances = new HashMap<>();
 
         MultiResponseHandler balancesMultiResponse = new MultiResponseHandler(accounts.length);
@@ -114,7 +113,7 @@ public class BalanceHelper {
             NetworkInfo selectedNetwork,
             AccountInfo[] accountInfos,
             BlockchainToken[] tokens,
-            Callbacks.Callback2<Integer, HashMap<String, HashMap<String, Double>>> callback) {
+            AsyncUtils.Callback2<Integer, HashMap<String, HashMap<String, Double>>> callback) {
         if (jsonRpcService == null) return;
         HashMap<String, HashMap<String, Double>> blockchainTokensBalances =
                 new HashMap<String, HashMap<String, Double>>();
@@ -222,7 +221,7 @@ public class BalanceHelper {
             WeakReference<BraveWalletBaseActivity> activityRef,
             List<NetworkInfo> allNetworks,
             NetworkInfo selectedNetwork,
-            Callbacks.Callback1<HashMap<Integer, HashSet<String>>> callback) {
+            AsyncUtils.Callback1<HashMap<Integer, HashSet<String>>> callback) {
         BraveWalletBaseActivity activity = activityRef.get();
         if (activity == null || activity.isFinishing()) return;
         KeyringService keyringService = activity.getKeyringService();
@@ -234,13 +233,16 @@ public class BalanceHelper {
                 && keyringService != null
                 && jsonRpcService != null;
         if (JavaUtils.anyNull(
-                braveWalletService, blockchainRegistry, keyringService, jsonRpcService)) return;
+                braveWalletService, blockchainRegistry, keyringService, jsonRpcService)) {
+            return;
+        }
 
         boolean P3AEnabled = BraveLocalState.get().getBoolean(BravePref.P3A_ENABLED);
 
         HashMap<Integer, HashSet<String>> activeAddresses = new HashMap<Integer, HashSet<String>>();
-        for (int coinType : Utils.P3ACoinTypes)
+        for (int coinType : Utils.P3ACoinTypes) {
             activeAddresses.put(coinType, new HashSet<String>());
+        }
 
         if (!P3AEnabled) {
             callback.call(activeAddresses);
@@ -392,16 +394,18 @@ public class BalanceHelper {
             HashMap<Integer, HashSet<String>> activeAddresses) {
         for (GetNativeAssetsBalancesResponseContext ctx : nativeAssetsBalancesResponses) {
             for (Map.Entry<String, Double> nativeEntry : ctx.nativeAssetsBalances.entrySet()) {
-                if (nativeEntry.getValue() > 0.0d)
+                if (nativeEntry.getValue() > 0.0d) {
                     activeAddresses.get(ctx.coinType).add(nativeEntry.getKey());
+                }
             }
         }
         for (GetBlockchainTokensBalancesResponseContext ctx : blockchainTokensBalancesResponses) {
             for (Map.Entry<String, HashMap<String, Double>> accEntry :
                     ctx.blockchainTokensBalances.entrySet()) {
                 for (Map.Entry<String, Double> tokenEntry : accEntry.getValue().entrySet()) {
-                    if (tokenEntry.getValue() > 0.0d)
+                    if (tokenEntry.getValue() > 0.0d) {
                         activeAddresses.get(ctx.coinType).add(accEntry.getKey());
+                    }
                 }
             }
         }
diff --git a/android/java/org/chromium/chrome/browser/crypto_wallet/util/TokenUtils.java b/android/java/org/chromium/chrome/browser/crypto_wallet/util/TokenUtils.java
index 9bf69f0d149..41a975f27a8 100644
--- a/android/java/org/chromium/chrome/browser/crypto_wallet/util/TokenUtils.java
+++ b/android/java/org/chromium/chrome/browser/crypto_wallet/util/TokenUtils.java
@@ -8,7 +8,6 @@ package org.chromium.chrome.browser.crypto_wallet.util;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
-import org.chromium.base.Callbacks;
 import org.chromium.brave_wallet.mojom.BlockchainRegistry;
 import org.chromium.brave_wallet.mojom.BlockchainToken;
 import org.chromium.brave_wallet.mojom.BraveWalletService;
@@ -22,6 +21,16 @@ import java.util.List;
 import java.util.stream.Stream;
 
 public class TokenUtils {
+    /**
+     * A generic 1-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     */
+    public interface Callback1<T1> {
+        /** Call the callback. */
+        void call(T1 arg1);
+    }
+
     /**
      * Type of token used for filtering an array of {@code BlockchainToken}.
      *
@@ -125,7 +134,7 @@ public class TokenUtils {
             NetworkInfo selectedNetwork,
             int coinType,
             TokenType tokenType,
-            Callbacks.Callback1<BlockchainToken[]> callback) {
+            Callback1<BlockchainToken[]> callback) {
         braveWalletService.getUserAssets(
                 selectedNetwork.chainId,
                 coinType,
@@ -151,7 +160,7 @@ public class TokenUtils {
             @Nullable BlockchainRegistry blockchainRegistry,
             @Nullable NetworkInfo selectedNetwork,
             TokenType tokenType,
-            Callbacks.Callback1<BlockchainToken[]> callback) {
+            Callback1<BlockchainToken[]> callback) {
         if (braveWalletService == null || blockchainRegistry == null || selectedNetwork == null) {
             return;
         }
@@ -181,7 +190,7 @@ public class TokenUtils {
             int coinType,
             TokenType tokenType,
             boolean userAssetsOnly,
-            Callbacks.Callback1<BlockchainToken[]> callback) {
+            Callback1<BlockchainToken[]> callback) {
         if (JavaUtils.anyNull(braveWalletService, blockchainRegistry)) return;
         if (userAssetsOnly) {
             getVisibleUserAssetsFiltered(
diff --git a/android/java/org/chromium/chrome/browser/crypto_wallet/util/Utils.java b/android/java/org/chromium/chrome/browser/crypto_wallet/util/Utils.java
index 870766e3cc1..6c1bbe318f4 100644
--- a/android/java/org/chromium/chrome/browser/crypto_wallet/util/Utils.java
+++ b/android/java/org/chromium/chrome/browser/crypto_wallet/util/Utils.java
@@ -41,7 +41,6 @@ import org.json.JSONException;
 import org.json.JSONObject;
 
 import org.chromium.base.ApiCompatibilityUtils;
-import org.chromium.base.Callbacks;
 import org.chromium.base.CommandLine;
 import org.chromium.base.Log;
 import org.chromium.base.shared_preferences.SharedPreferencesManager;
@@ -1124,7 +1123,7 @@ public class Utils {
             AccountInfo[] accountInfos,
             BlockchainToken[] filterByTokens,
             boolean userAssetsOnly,
-            Callbacks.Callback4<
+            AsyncUtils.Callback4<
                             List<AssetPrice>,
                             BlockchainToken[],
                             HashMap<String, Double>,
@@ -1222,7 +1221,7 @@ public class Utils {
      * @param callback Callback containing a filtered list of P3A networks.
      */
     public static void getP3ANetworks(
-            List<NetworkInfo> allNetworks, Callbacks.Callback1<List<NetworkInfo>> callback) {
+            List<NetworkInfo> allNetworks, AsyncUtils.Callback1<List<NetworkInfo>> callback) {
         ArrayList<NetworkInfo> relevantNetworks = new ArrayList<NetworkInfo>();
         boolean countTestNetworks =
                 CommandLine.getInstance()
diff --git a/android/java/org/chromium/chrome/browser/settings/BraveWalletNetworksPreference.java b/android/java/org/chromium/chrome/browser/settings/BraveWalletNetworksPreference.java
index 2486a2050dd..588dcbec274 100644
--- a/android/java/org/chromium/chrome/browser/settings/BraveWalletNetworksPreference.java
+++ b/android/java/org/chromium/chrome/browser/settings/BraveWalletNetworksPreference.java
@@ -18,7 +18,6 @@ import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
 import org.chromium.base.Callback;
-import org.chromium.base.Callbacks;
 import org.chromium.brave_wallet.mojom.CoinType;
 import org.chromium.brave_wallet.mojom.JsonRpcService;
 import org.chromium.brave_wallet.mojom.NetworkInfo;
@@ -36,6 +35,19 @@ import java.util.Arrays;
 public class BraveWalletNetworksPreference extends Preference
         implements ConnectionErrorHandler, NetworkPreferenceAdapter.ItemClickListener {
 
+    /**
+     * A generic 4-argument callback.
+     *
+     * @param <T1> The type of the first argument.
+     * @param <T2> The type of the second argument.
+     * @param <T3> The type of the third argument.
+     * @param <T4> The type of the fourth argument.
+     */
+    public interface Callback4<T1, T2, T3, T4> {
+        /** Call the callback. */
+        void call(T1 arg1, T2 arg2, T3 arg3, T4 arg4);
+    }
+
     private AppCompatButton mAddNetwork;
     private RecyclerView mRecyclerView;
     @Nullable private BraveWalletAddNetworksFragment.Listener mListener;
@@ -211,8 +223,7 @@ public class BraveWalletNetworksPreference extends Preference
      */
     private void getAvailableChainIds(
             @CoinType.EnumType final int coinType,
-            @NonNull
-                    final Callbacks.Callback4<String, NetworkInfo[], String[], String[]> callback) {
+            @NonNull final Callback4<String, NetworkInfo[], String[], String[]> callback) {
         mJsonRpcService.getDefaultChainId(
                 coinType,
                 defaultChainId ->