[Android] Fixes for lint new warnings

List of the fixed warning types:
warning: [ClassCanBeStatic] Inner class is non-static but does not reference enclosing class
warning: [AlmostJavadoc] This comment contains Javadoc or HTML tags, but isn't started with a double asterisk
warning: [EmptyBlockTag] A block tag (@param, @return, @throws, @deprecated) has an empty description. Block tags without descriptions don't add much value for future readers of the code; consider removing the tag entirely or adding a description.
warning: [ObjectToString] DisplayAd is final and does not override Object.toString, so converting it to a string will print its identity (e.g. `DisplayAd@4488aabb`) instead of useful information.

android/java/org/chromium/chrome/browser/BraveRewardsHelper.java

@@ -506,11 +506,13 @@ public class BraveRewardsHelper implements LargeIconBridge.LargeIconCallback {
 
     /**
      * Expands touchable area of a small view
-      * @param parentView
-     * @param childView
-     * @param extraPadding: dp
+     *
+     * @param parentView Parent view.
+     * @param childView Child view.
+     * @param extraPadding Extra padding in dp.
      */
-  public static void expandTouchArea(final View parentView, final View childView, final int extraPadding) {
+    public static void expandTouchArea(
+            final View parentView, final View childView, final int extraPadding) {
         parentView.post(new Runnable() {
             @Override
             public void run() {
@@ -527,11 +529,7 @@ public class BraveRewardsHelper implements LargeIconBridge.LargeIconCallback {
         });
     }
 
-    /**
-     * Converts DP into PX
-     * @param dp
-     * @return
-     */
+    /** Converts DP into PX */
     public static int dp2px(int dp) {
         DisplayMetrics metrics = Resources.getSystem().getDisplayMetrics();
         float px = dp * (metrics.densityDpi / DP_PER_INCH_MDPI);

android/java/org/chromium/chrome/browser/brave_news/models/FeedItemCard.java

@@ -40,6 +40,7 @@ public class FeedItemCard {
         this.imageByte = imageByte;
     }
 
+    @SuppressWarnings("ObjectToString")
     @Override
     public String toString() {
         return "FeedItemCard{"

android/java/org/chromium/chrome/browser/brave_news/models/FeedItemsCard.java

@@ -70,6 +70,7 @@ public class FeedItemsCard {
         this.displayAd = displayAd;
     }
 
+    @SuppressWarnings("ObjectToString")
     @Override
     public String toString() {
         return "FeedItemsCard{"

android/java/org/chromium/chrome/browser/custom_layout/NonSwipeableViewPager.java

@@ -54,7 +54,7 @@ public class NonSwipeableViewPager extends ViewPager {
         }
     }
 
-    public class ViewPagerScroller extends Scroller {
+    public static class ViewPagerScroller extends Scroller {
         ViewPagerScroller(Context context) {
             super(context, new DecelerateInterpolator());
         }

android/java/org/chromium/chrome/browser/qrreader/CameraSource.java

@@ -657,10 +657,8 @@ public class CameraSource {
     private CameraSource() {
     }
 
-    /**
-     * Wraps the camera1 shutter callback so that the deprecated API isn't exposed.
-     */
-    private class PictureStartCallback implements Camera.ShutterCallback {
+    /** Wraps the camera1 shutter callback so that the deprecated API isn't exposed. */
+    private static class PictureStartCallback implements Camera.ShutterCallback {
         private ShutterCallback mDelegate;
 
         @Override
@@ -691,10 +689,8 @@ public class CameraSource {
         }
     }
 
-    /**
-     * Wraps the camera1 auto focus callback so that the deprecated API isn't exposed.
-     */
-    private class CameraAutoFocusCallback implements Camera.AutoFocusCallback {
+    /** Wraps the camera1 auto focus callback so that the deprecated API isn't exposed. */
+    private static class CameraAutoFocusCallback implements Camera.AutoFocusCallback {
         private AutoFocusCallback mDelegate;
 
         @Override
@@ -705,11 +701,9 @@ public class CameraSource {
         }
     }
 
-    /**
-     * Wraps the camera1 auto focus move callback so that the deprecated API isn't exposed.
-     */
+    /** Wraps the camera1 auto focus move callback so that the deprecated API isn't exposed. */
     @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
-    private class CameraAutoFocusMoveCallback implements Camera.AutoFocusMoveCallback {
+    private static class CameraAutoFocusMoveCallback implements Camera.AutoFocusMoveCallback {
         private AutoFocusMoveCallback mDelegate;
 
         @Override

android/java/org/chromium/chrome/browser/sync/BraveSyncDevices.java

@@ -103,7 +103,7 @@ public class BraveSyncDevices {
         }
     }
 
-    public class SyncDeviceInfo {
+    public static class SyncDeviceInfo {
         public String mName;
         public boolean mIsCurrentDevice;
         public boolean mSupportsSelfDelete;

android/java/org/chromium/chrome/browser/util/TabUtils.java

@@ -318,11 +318,7 @@ public class TabUtils {
         context.startActivity(intent);
     }
 
-    /**
-     * Returns transition for the given tab
-     *
-     * @param tab
-     */
+    /** Returns transition for the given tab */
     public static int getTransition(Tab tab) {
         if (tab != null
                 && tab.getWebContents() != null