Refactor audio manager for Android to avoid heavy tasks at startup

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 <set>
 
 #include "base/android/jni_android.h"
@@ skipping 49 matching lines @@
   void SetMute(JNIEnv* env, jobject obj, jboolean muted);
 
  protected:
   virtual ~AudioManagerAndroid();
 
   virtual AudioParameters GetPreferredOutputStreamParameters(
       const std::string& output_device_id,
       const AudioParameters& input_params) OVERRIDE;
 
  private:
+  bool IsFirstCreatedAudioStream();

[tommi (sloooow) - chröme, 2013/12/10 21:19:11]

HasOneAudioStream?
(IsFirstXxx sounds like it would need a stream argument to check if that stream
is the first one)

[henrika (OOO until Aug 14), 2013/12/11 13:16:38]

Removed.

+  bool IsLastDestroyedAudioStream();

[tommi (sloooow) - chröme, 2013/12/10 21:19:11]

It's not clear how this is different from the function above, so would be good
to have some documentation.
Also, do you need to clarify whether it's an input or output stream?

[henrika (OOO until Aug 14), 2013/12/11 13:16:38]

Renamed.

Regarding input & output. The old solution (before I did any work) only set the
audio mode to comm mode when out stream was created, hence no mode shift if only
capture was active. It feels wrong so my idea was to maintain the mode as long
as any stream needs it.

[tommi (sloooow) - chröme, 2013/12/11 17:25:05]

sgtm

   void Init();
   void Close();
-  void SetAudioMode(int mode);
-  void SetAudioDevice(const std::string& device_id);
+  void SetCommunicationAudioModeOn(bool on);
+  bool SetAudioDevice(const std::string& device_id);
   int GetNativeOutputSampleRate();
   bool IsAudioLowLatencySupported();
   int GetAudioLowLatencyOutputFrameSize();
   int GetOptimalOutputFrameSize(int sample_rate, int channels);
 
   void DoSetMuteOnAudioThread(bool muted);
 
   // Allow the AudioAndroidTest to access private methods.
   FRIEND_TEST_ALL_PREFIXES(AudioAndroidTest, IsAudioLowLatencySupported);
 
   // Java AudioManager instance.
   base::android::ScopedJavaGlobalRef<jobject> j_audio_manager_;
 
   typedef std::set<OpenSLESOutputStream*> OutputStreams;
   OutputStreams streams_;
   // TODO(wjia): remove this lock once unit test modules are fixed to call
   // AudioManager::MakeAudioOutputStream on the audio thread. For now, this
   // lock is used to guard access to |streams_|.
   base::Lock streams_lock_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerAndroid);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_ANDROID_AUDIO_MANAGER_ANDROID_H_