Add feature flag for Custom Search Engines.

Flag for the new feature that allows user to add custom search engines in
settings.

Bug: 433824
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Change-Id: If3b91e276b752b546013644119a5560f0a486314
Reviewed-on: https://chromium-review.googlesource.com/1236314
Commit-Queue: Yi Su <mrsuyi@chromium.org>
Reviewed-by: Eric Noyau <noyau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593591}

ios/chrome/browser/BUILD.gn

@@ -124,6 +124,7 @@ source_set("browser") {
     "//ios/chrome/browser/itunes_urls",
     "//ios/chrome/browser/mailto:feature_flags",
     "//ios/chrome/browser/payments:constants",
+    "//ios/chrome/browser/search_engines:feature_flags",
     "//ios/chrome/browser/signin:feature_flags",
     "//ios/chrome/browser/ssl:feature_flags",
     "//ios/chrome/browser/sync/glue",

ios/chrome/browser/about_flags.mm

@@ -47,6 +47,7 @@
 #include "ios/chrome/browser/ios_chrome_flag_descriptions.h"
 #include "ios/chrome/browser/itunes_urls/itunes_urls_flag.h"
 #include "ios/chrome/browser/mailto/features.h"
+#include "ios/chrome/browser/search_engines/feature_flags.h"
 #include "ios/chrome/browser/signin/feature_flags.h"
 #include "ios/chrome/browser/ssl/captive_portal_features.h"
 #include "ios/chrome/browser/ui/external_search/features.h"
@@ -391,6 +392,9 @@ const flags_ui::FeatureEntry kFeatureEntries[] = {
     {"wk-web-view-snapshots", flag_descriptions::kWKWebViewSnapshotsName,
      flag_descriptions::kWKWebViewSnapshotsDescription, flags_ui::kOsIos,
      FEATURE_VALUE_TYPE(kWKWebViewSnapshots)},
+    {"custom-search-engines", flag_descriptions::kCustomSearchEnginesName,
+     flag_descriptions::kCustomSearchEnginesDescription, flags_ui::kOsIos,
+     FEATURE_VALUE_TYPE(kCustomSearchEngines)},
 };
 
 // Add all switches from experimental flags to |command_line|.

ios/chrome/browser/ios_chrome_flag_descriptions.cc

@@ -304,6 +304,10 @@ const char kWKWebViewSnapshotsName[] = "WKWebView Snapshots";
 const char kWKWebViewSnapshotsDescription[] =
     "When enabled, the WKWebView snapshotting API is used for iOS 11+.";
 
+const char kCustomSearchEnginesName[] = "Custom Search Engines";
+const char kCustomSearchEnginesDescription[] =
+    "When enabled, user can add custom search engines in settings.";
+
 // Please insert your name/description above in alphabetical order.
 
 }  // namespace flag_descriptions

ios/chrome/browser/ios_chrome_flag_descriptions.h

@@ -255,6 +255,10 @@ extern const char kWKHTTPSystemCookieStoreDescription[];
 extern const char kWKWebViewSnapshotsName[];
 extern const char kWKWebViewSnapshotsDescription[];
 
+// Title and description for the flag to allow custom search engines.
+extern const char kCustomSearchEnginesName[];
+extern const char kCustomSearchEnginesDescription[];
+
 // Please insert your name/description above in alphabetical order.
 
 }  // namespace flag_descriptions

ios/chrome/browser/search_engines/BUILD.gn

@@ -5,6 +5,17 @@
 import("//build/config/features.gni")
 import("//rlz/buildflags/buildflags.gni")
 
+source_set("feature_flags") {
+  configs += [ "//build/config/compiler:enable_arc" ]
+  sources = [
+    "feature_flags.cc",
+    "feature_flags.h",
+  ]
+  deps = [
+    "//base",
+  ]
+}
+
 source_set("search_engines") {
   sources = [
     "search_engine_observer_bridge.h",

ios/chrome/browser/search_engines/feature_flags.cc

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ios/chrome/browser/search_engines/feature_flags.h"
+
+const base::Feature kCustomSearchEngines{"CustomSearchEngines",
+                                         base::FEATURE_DISABLED_BY_DEFAULT};

ios/chrome/browser/search_engines/feature_flags.h

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef IOS_CHROME_BROWSER_SEARCH_ENGINES_FEATURE_FLAGS_H_
+#define IOS_CHROME_BROWSER_SEARCH_ENGINES_FEATURE_FLAGS_H_
+
+#include "base/feature_list.h"
+
+// Feature to allow user to add custom search engines.
+extern const base::Feature kCustomSearchEngines;
+
+#endif  // IOS_CHROME_BROWSER_SEARCH_ENGINES_FEATURE_FLAGS_H_