Add a new audio extension event OnLevelChanged.

extensions/browser/api/audio/audio_api.h

 // Copyright (c) 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 EXTENSIONS_BROWSER_API_AUDIO_AUDIO_API_H_
 #define EXTENSIONS_BROWSER_API_AUDIO_AUDIO_API_H_
 
 #include "extensions/browser/api/audio/audio_service.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
 #include "extensions/browser/extension_function.h"
 
 namespace extensions {
 
 class AudioService;
 
 class AudioAPI : public BrowserContextKeyedAPI, public AudioService::Observer {
  public:
   explicit AudioAPI(content::BrowserContext* context);
   ~AudioAPI() override;
 
   AudioService* GetService() const;
 
   // BrowserContextKeyedAPI implementation.
   static BrowserContextKeyedAPIFactory<AudioAPI>* GetFactoryInstance();
 
   // AudioService::Observer implementation.
   void OnDeviceChanged() override;
+  void OnOutputNodeVolumeChanged(const std::string& id, double volume) override;
 
  private:
   friend class BrowserContextKeyedAPIFactory<AudioAPI>;
 
   // BrowserContextKeyedAPI implementation.
   static const char* service_name() {
     return "AudioAPI";
   }
 
   content::BrowserContext* const browser_context_;
@@ skipping 25 matching lines @@
 
 class AudioSetPropertiesFunction : public SyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION("audio.setProperties", AUDIO_SETPROPERTIES);
 
  protected:
   ~AudioSetPropertiesFunction() override {}
   bool RunSync() override;
 };
 
+class AudioGetDeviceInfoFunction : public AsyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("audio.getDeviceInfo", AUDIO_GETDEVICEINFO);
+
+ protected:
+  ~AudioGetDeviceInfoFunction() override {}
+  bool RunAsync() override;
+
+ private:
+  void OnGetDeviceInfoCompleted(const DevicesInfo& devices_info, bool success);
+};
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_AUDIO_AUDIO_API_H_