Updates the mic icon status based on the device's audio state.

chrome/browser/ui/app_list/start_page_service.h

 // Copyright 2013 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 CHROME_BROWSER_UI_APP_LIST_START_PAGE_SERVICE_H_
 #define CHROME_BROWSER_UI_APP_LIST_START_PAGE_SERVICE_H_
 
 #include <stdint.h>
 #include <vector>
 
@@ skipping 70 matching lines @@
 
   // ProfileDestroyObserver to shutdown the service on exiting. WebContents
   // depends on the profile and needs to be closed before the profile and its
   // keyed service shutdown.
   class ProfileDestroyObserver;
 
   // The WebContentsDelegate implementation for the start page. This allows
   // getUserMedia() request from the web contents.
   class StartPageWebContentsDelegate;
 
+#if defined(OS_CHROMEOS)
+  // This class observes the change of audio input device availability and
+  // checks if currently the system has valid audio input.
+  class AudioStatus;
+#endif
+
   void LoadContents();
   void UnloadContents();
 
   // KeyedService overrides:
   void Shutdown() override;
 
   Profile* profile_;
   scoped_ptr<content::WebContents> contents_;
   scoped_ptr<StartPageWebContentsDelegate> contents_delegate_;
   scoped_ptr<ProfileDestroyObserver> profile_destroy_observer_;
   scoped_ptr<RecommendedApps> recommended_apps_;
   SpeechRecognitionState state_;
   ObserverList<StartPageObserver> observers_;
   bool speech_button_toggled_manually_;
   bool speech_result_obtained_;
 
   bool webui_finished_loading_;
   std::vector<base::Closure> pending_webui_callbacks_;
 
   scoped_ptr<SpeechRecognizer> speech_recognizer_;
 
+#if defined(OS_CHROMEOS)
+  scoped_ptr<AudioStatus> audio_status_;
+#endif
+
   base::WeakPtrFactory<StartPageService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(StartPageService);
 };
 
 }  // namespace app_list
 
 #endif  // CHROME_BROWSER_UI_APP_LIST_START_PAGE_SERVICE_H_