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>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/strings/string16.h"
 #include "chrome/browser/ui/app_list/speech_recognizer_delegate.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "content/public/browser/web_contents.h"
 #include "ui/app_list/speech_ui_model_observer.h"
 
+#if defined(OS_CHROMEOS)
+#include "chromeos/audio/cras_audio_handler.h"
+#endif
+
 namespace extensions {
 class Extension;
 }
 
 class Profile;
 
 namespace app_list {
 
 class RecommendedApps;
 class SpeechRecognizer;
 class StartPageObserver;
 
 // StartPageService collects data to be displayed in app list's start page
 // and hosts the start page contents.
 class StartPageService : public KeyedService,
-                         public SpeechRecognizerDelegate {
+                         public SpeechRecognizerDelegate,

[tapted, 2014/11/25 05:03:11]

does this trailing comma break things?

I'm not really a fan of guarding parent classes with #ifdef - the code gets
unmaintainable quite quickly. Getting my head around all the speech-recognition
states is already quite hard.

It actually would't be too hard to subclass StartPageService with a
StartPageServiceChromeOS and just #ifdef around `new StartPageService(..)` and a
#include in start_page_service_factory.cc -- Can we do that?

Then make StartPageService::AppListShown virtual, or have AppListShown call
OnAppListShown at the end.


StartPageService::Create(Profile*) is another option. Then in
start_page_service.cc you would just need 

#if !defined(OS_CHROMEOS)
StartPageService* StartPageService::Create(Profile* profile) {
  return new StartPageService(profile);
}
#endif


with StartPageServiceChromeOS being provided in start_page_service_chromeos.cc

[Jun Mukai, 2014/11/26 01:39:21]

You are right.
I think StartPageServiceChromeOS is an overkill in this situation -- I factored
out the audio handling code into an internal class, named AudioDeviceStatus. 
WDYT?

[tapted, 2014/11/26 02:05:58]

looks good!

+#if defined(OS_CHROMEOS)
+                         public chromeos::CrasAudioHandler::AudioObserver
+#endif
+                         {
  public:
   typedef std::vector<scoped_refptr<const extensions::Extension> >
       ExtensionList;
   // Gets the instance for the given profile.
   static StartPageService* Get(Profile* profile);
 
   void AddObserver(StartPageObserver* observer);
   void RemoveObserver(StartPageObserver* observer);
 
   void AppListShown();
@@ skipping 38 matching lines @@
   // The WebContentsDelegate implementation for the start page. This allows
   // getUserMedia() request from the web contents.
   class StartPageWebContentsDelegate;
 
   void LoadContents();
   void UnloadContents();
 
   // KeyedService overrides:
   void Shutdown() override;
 
+#if defined(OS_CHROMEOS)
+  // chromeos::CrasAudioHandler::AudioObserver:
+  void OnInputMuteChanged() override;
+  void OnActiveInputNodeChanged() override;
+#endif
+
   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_;
 
   base::WeakPtrFactory<StartPageService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(StartPageService);
 };
 
 }  // namespace app_list
 
 #endif  // CHROME_BROWSER_UI_APP_LIST_START_PAGE_SERVICE_H_