Add MODIFY_AUDIO_SETTINGS permission in Android manifest and implementation in audio manager.

media/audio/android/audio_manager_android.h

 // Copyright (c) 2012 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 MEDIA_AUDIO_ANDROID_AUDIO_MANAGER_ANDROID_H_
 #define MEDIA_AUDIO_ANDROID_AUDIO_MANAGER_ANDROID_H_
 
+#include "base/android/jni_android.h"
 #include "media/audio/audio_manager_base.h"
 
 namespace media {
 
 // Android implemention of AudioManager.
 class MEDIA_EXPORT AudioManagerAndroid : public AudioManagerBase {
  public:
+  static const int kAudioModeNormal = 0x00000000;
+  static const int kAudioModeRingtone = 0x00000001;

[qinmin, 2013/03/11 23:09:56]

be specific, i don't think it is proper for chrome to change Ringtone and InCall
volumes.
And you can define the remaining 2 constants in .cc file

[leozwang1, 2013/03/12 22:23:00]

Done.

+  static const int kAudioModeInCall = 0x00000002;
+  static const int kAudioModeInCommunication = 0x00000003;
+
   AudioManagerAndroid();
 
   // Implementation of AudioManager.
   virtual bool HasAudioOutputDevices() OVERRIDE;
   virtual bool HasAudioInputDevices() OVERRIDE;
   virtual void GetAudioInputDeviceNames(media::AudioDeviceNames* device_names)
       OVERRIDE;
   virtual AudioParameters GetInputStreamParameters(
       const std::string& device_id) OVERRIDE;
 
   // Implementation of AudioManagerBase.
   virtual AudioOutputStream* MakeLinearOutputStream(
       const AudioParameters& params) OVERRIDE;
   virtual AudioOutputStream* MakeLowLatencyOutputStream(
       const AudioParameters& params) OVERRIDE;
   virtual AudioInputStream* MakeLinearInputStream(
       const AudioParameters& params, const std::string& device_id) OVERRIDE;
   virtual AudioInputStream* MakeLowLatencyInputStream(
       const AudioParameters& params, const std::string& device_id) OVERRIDE;
 
+  static bool RegisterAudioManager(JNIEnv* env);
+
  protected:
   virtual ~AudioManagerAndroid();
 
   virtual AudioParameters GetPreferredOutputStreamParameters(
       const AudioParameters& input_params) OVERRIDE;
+  void SetAudioMode(int mode);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AudioManagerAndroid);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_ANDROID_AUDIO_MANAGER_ANDROID_H_