Add a flag for IME options page in ChromeOS settings.

Implemented a UI change behind the flag:
UI with flag disabled: https://screenshot.googleplex.com/osdAbRsrOdw
UI with flag enabled: https://screenshot.googleplex.com/k9waaRkjG4x

Test: tested with Chrome on Linux
Bug: 1086786
Change-Id: Id3b35306289715e8761e874a6b0fcdfed12205ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2216139Reviewed-by: Darren Shen <shend@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Jing Wang <jiwan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#773047}

chrome/browser/resources/settings/chromeos/os_languages_page/os_languages_page.html

@@ -138,6 +138,7 @@
         margin-inline-start: var(--settings-controlled-by-spacing);
       }
 
+      .internal-wrapper,
       .external-wrapper {
         display: flex;
       }
@@ -215,11 +216,18 @@
                 $i18n{inputMethodEnabled}
               </div>
             </div>
-            <div class="external-wrapper" hidden="[[!item.hasOptionsPage]]">
-              <div class="separator"></div>
-              <cr-icon-button class="icon-external"
-                  on-click="onInputMethodOptionsTap_"></cr-icon-button>
-            </div>
+            <template is="dom-if" if="[[imeOptionsInSettings_]]">
+              <div class="internal-wrapper" hidden="[[!item.hasOptionsPage]]">
+                <cr-icon-button class="subpage-arrow"></cr-icon-button>
+              </div>
+            </template>
+            <template is="dom-if" if="[[!imeOptionsInSettings_]]">
+              <div class="external-wrapper" hidden="[[!item.hasOptionsPage]]">
+                <div class="separator"></div>
+                <cr-icon-button class="icon-external"
+                    on-click="onInputMethodOptionsTap_"></cr-icon-button>
+              </div>
+            </template>
           </div>
         </template>
         <cr-link-row class="hr list-item" id="manageInputMethods"

chrome/browser/resources/settings/chromeos/os_languages_page/os_languages_page.js

@@ -66,6 +66,14 @@ cr.define('settings', function() {
           return loadTimeData.getBoolean('isGuest');
         },
       },
+
+      /** @private */
+      imeOptionsInSettings_: {
+        type: Boolean,
+        value() {
+          return loadTimeData.getBoolean('imeOptionsInSettings');
+        },
+      }
     },
 
     /** @private {boolean} */

chrome/browser/ui/webui/settings/chromeos/languages_section.cc

@@ -154,6 +154,9 @@ void LanguagesSection::AddLoadTimeData(content::WebUIDataSource* html_source) {
   html_source->AddString(
       "languagesLearnMoreURL",
       base::ASCIIToUTF16(chrome::kLanguageSettingsLearnMoreUrl));
+  html_source->AddBoolean("imeOptionsInSettings",
+                          base::FeatureList::IsEnabled(
+                              ::chromeos::features::kImeOptionsInSettings));
 }
 
 void LanguagesSection::AddHandlers(content::WebUI* web_ui) {

chromeos/constants/chromeos_features.cc

@@ -79,6 +79,11 @@ const base::Feature kBluetoothNextHandsfreeProfile{
 const base::Feature kCameraSystemWebApp{"CameraSystemWebApp",
                                         base::FEATURE_DISABLED_BY_DEFAULT};
 
+// If enabled, options page for each input method will be opened in ChromeOS
+// settings. Otherwise it will be opened in a new web page in Chrome browser.
+const base::Feature kImeOptionsInSettings{"ImeOptionsInSettings",
+                                          base::FEATURE_DISABLED_BY_DEFAULT};
+
 // Enables or disables Crostini port forwarding.
 const base::Feature kCrostiniPortForwarding{"CrostiniPortForwarding",
                                             base::FEATURE_DISABLED_BY_DEFAULT};

chromeos/constants/chromeos_features.h

@@ -107,6 +107,8 @@ extern const base::Feature kImeInputLogicFst;
 COMPONENT_EXPORT(CHROMEOS_CONSTANTS)
 extern const base::Feature kImeInputLogicMozc;
 COMPONENT_EXPORT(CHROMEOS_CONSTANTS)
+extern const base::Feature kImeOptionsInSettings;
+COMPONENT_EXPORT(CHROMEOS_CONSTANTS)
 extern const base::Feature kVirtualKeyboardFloatingDefault;
 COMPONENT_EXPORT(CHROMEOS_CONSTANTS)
 extern const base::Feature kInstantTethering;