Introduce brave vpn feature flag

fix https://github.com/brave/brave-browser/issues/17108

We will implement brave vpn behind this feature flag.

components/brave_vpn/BUILD.gn

@@ -3,6 +3,8 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this file,
 # You can obtain one at http://mozilla.org/MPL/2.0/.
 
+import("//brave/components/brave_vpn/buildflags/buildflags.gni")
+
 static_library("brave_vpn") {
   sources = [
     "brave_vpn_connection_info.cc",
@@ -11,6 +13,8 @@ static_library("brave_vpn") {
     "brave_vpn_connection_manager.h",
     "brave_vpn_service.cc",
     "brave_vpn_service.h",
+    "features.cc",
+    "features.h",
   ]
 
   deps = [
@@ -63,6 +67,21 @@ source_set("brave_vpn_internal") {
   }
 }
 
+source_set("unit_tests") {
+  if (enable_brave_vpn) {
+    testonly = true
+
+    sources = [ "brave_vpn_unittest.cc" ]
+
+    deps = [
+      ":brave_vpn",
+      "//base",
+      "//content/test:test_support",
+      "//testing/gtest",
+    ]
+  }
+}
+
 executable("vpntool") {
   sources = []
   deps = [

components/brave_vpn/brave_vpn_unittest.cc

@@ -0,0 +1,17 @@
+/* Copyright (c) 2021 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 http://mozilla.org/MPL/2.0/. */
+
+#include "base/feature_list.h"
+#include "brave/components/brave_vpn/features.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace brave_vpn {
+
+TEST(BraveVPNTest, Basic) {
+  // Disable by default till we implement all brave vpn features.
+  EXPECT_FALSE(base::FeatureList::IsEnabled(kBraveVPNFeature));
+}
+
+}  // namespace brave_vpn

components/brave_vpn/features.cc

@@ -0,0 +1,15 @@
+/* Copyright (c) 2021 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 http://mozilla.org/MPL/2.0/. */
+
+#include "brave/components/brave_vpn/features.h"
+
+#include "base/feature_list.h"
+
+namespace brave_vpn {
+
+const base::Feature kBraveVPNFeature{"BraveVPN",
+                                     base::FEATURE_DISABLED_BY_DEFAULT};
+
+}  // namespace brave_vpn

components/brave_vpn/features.h

@@ -0,0 +1,19 @@
+/* Copyright (c) 2021 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 http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_VPN_FEATURES_H_
+#define BRAVE_COMPONENTS_BRAVE_VPN_FEATURES_H_
+
+namespace base {
+struct Feature;
+}  // namespace base
+
+namespace brave_vpn {
+
+extern const base::Feature kBraveVPNFeature;
+
+}  // namespace brave_vpn
+
+#endif  // BRAVE_COMPONENTS_BRAVE_VPN_FEATURES_H_

test/BUILD.gn

@@ -180,6 +180,7 @@ test("brave_unit_tests") {
     "//brave/components/brave_search/common",
     "//brave/components/brave_shields/browser",
     "//brave/components/brave_shields/common",
+    "//brave/components/brave_vpn:unit_tests",
     "//brave/components/brave_wallet/browser/test:brave_wallet_unit_tests",
     "//brave/components/brave_wallet/common/buildflags",
     "//brave/components/child_process_monitor:unittests",