Add MediaCodecAudioDecoder implementation

media/filters/android/media_codec_audio_decoder.h

Index: media/filters/android/media_codec_audio_decoder.h
diff --git a/media/filters/android/media_codec_audio_decoder.h b/media/filters/android/media_codec_audio_decoder.h
index 1e307893a1534a617afb8b6a1489aa27795cc823..e012ef9e8e569c6d9f8c34f142232b8aaec77ac3 100644
--- a/media/filters/android/media_codec_audio_decoder.h
+++ b/media/filters/android/media_codec_audio_decoder.h
@@ -16,7 +16,6 @@
 #include "media/base/android/media_codec_bridge.h"
 #include "media/base/audio_decoder.h"
 #include "media/base/audio_decoder_config.h"
-#include "media/base/media_export.h"
 
 namespace base {
 class SingleThreadTaskRunner;
@@ -53,10 +52,15 @@ namespace media {
 // Because both dequeuing and enqueuing of an input buffer can fail, the
 // implementation puts the input |DecoderBuffer|s and the corresponding decode
 // callbacks into an input queue. The decoder has a timer that periodically
-// tries to send the front buffer from the input queue to the MediaCodec. In
-// the case of success the element is removed from the queue, the decode
-// callback is fired and the decoding process advances. The same timer tries to
-// dequeue an output buffer.
+// fires the decoding cycle that has two steps. The first step tries to send the
+// front buffer from the input queue to the MediaCodec. In the case of success
+// the element is removed from the queue, the decode callback is fired and the
+// decoding process advances. The second step tries to dequeue an output buffer,
+// and uses it in the case of success.
+//
+// The failures in both steps are normal and they happen periodically since

[Tima Vaisburd, 2016/02/11 20:23:23]

This is where I tried to clarify the timer function.

[xhwang, 2016/02/12 10:15:06]

Acknowledged.

+// both input and output buffers become available at unpredictable moments. The
+// timer is here to repeat the dequeueing attempts.
 //
 // Although one can specify a delay in the MediaCodec's dequeue operations,
 // this implementation follows the simple logic which is similar to
@@ -94,7 +98,7 @@ namespace media {
 //                 |                          |             |
 //              [Error]                    [Ready]       [Error]
 
-class MEDIA_EXPORT MediaCodecAudioDecoder : public AudioDecoder {
+class MediaCodecAudioDecoder : public AudioDecoder {

[xhwang, 2016/02/12 10:15:06]

You'll need MEDIA_EXPORT when you add unittest. I am not sure about Android
though.

[Tima Vaisburd, 2016/02/13 01:31:24]

Acknowledged.

  public:
   explicit MediaCodecAudioDecoder(
       const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
@@ -154,17 +158,12 @@ class MEDIA_EXPORT MediaCodecAudioDecoder : public AudioDecoder {
   // Helper method to change the state.
   void SetState(State new_state);
 
-  // The following helper methods ConfigureMediaCodec(), OnDecodedFrame(),
-  // OnOutputFormatChanged() are specific to the stream (audio/video), but
-  // others seem to apply to any MediaCodec decoder.
+  // The following helper methods OnDecodedFrame(),OnOutputFormatChanged() are
+  // specific to the stream (audio/video), but others seem to apply to any
+  // MediaCodec decoder.
   // TODO(timav): refactor the common part out and use it here and in AVDA
   // (http://crbug.com/583082).
 
-  // Configures MediaCodec with |config|. Returns valid MediaCodec pointer if
-  // succeeded or null if configuration failed.
-  scoped_ptr<MediaCodecBridge> ConfigureMediaCodec(
-      const AudioDecoderConfig& config);
-
   // Processes the output buffer after it comes from MediaCodec.
   void OnDecodedFrame(const OutputBufferInfo& out);