Use cached Key frames to avoid browser seek

media/base/android/media_decoder_job.h

Index: media/base/android/media_decoder_job.h
diff --git a/media/base/android/media_decoder_job.h b/media/base/android/media_decoder_job.h
index 9a3e76a5b27c5cda956958945316b198515d1ace..83ec5e1f559fa8dbc63b9e7b0d8d9e3ea454bfd3 100644
--- a/media/base/android/media_decoder_job.h
+++ b/media/base/android/media_decoder_job.h
@@ -27,6 +27,13 @@ class MediaDrmBridge;
 // data request will be sent to the renderer.
 class MediaDecoderJob {
  public:
+  // Return value when Decode() is called.
+  enum MediaDecoderJobStatus {
+    STATUS_SUCCESS,
+    STATUS_KEY_FRAME_REQUIRED,
+    STATUS_FAILURE,
+  };
+
   struct Deleter {
     inline void operator()(MediaDecoderJob* ptr) const { ptr->Release(); }
   };
@@ -57,13 +64,12 @@ class MediaDecoderJob {
   // Called by MediaSourcePlayer to decode some data.
   // |callback| - Run when decode operation has completed.
   //
-  // Returns true if the next decode was started and |callback| will be
-  // called when the decode operation is complete.
-  // Returns false if |media_codec_bridge_| cannot be created; |callback| is
-  // ignored and will not be called.
-  bool Decode(base::TimeTicks start_time_ticks,
-              base::TimeDelta start_presentation_timestamp,
-              const DecoderCallback& callback);
+  // Returns STATUS_SUCCESS on success, or STATUS_FAILURE on failure, or
+  // STATUS_KEY_FRAME_REQUIRED if a browser seek is required. |callback| is
+  // ignored and will not be called for the latter 2 cases.
+  MediaDecoderJobStatus Decode(base::TimeTicks start_time_ticks,
+                               base::TimeDelta start_presentation_timestamp,
+                               const DecoderCallback& callback);
 
   // Called to stop the last Decode() early.
   // If the decoder is in the process of decoding the next frame, then
@@ -132,6 +138,11 @@ class MediaDecoderJob {
   // Releases the |media_codec_bridge_|.
   void ReleaseMediaCodecBridge();
 
+  // Sets the current frame to a previously cached key frame. Returns true if
+  // a key frame is found, or false otherwise.
+  // TODO(qinmin): add UMA to study the cache hit ratio for key frames.
+  bool SetCurrentFrameToPreviouslyCachedKeyFrame();
+
   MediaDrmBridge* drm_bridge() { return drm_bridge_; }
 
   void set_is_content_encrypted(bool is_content_encrypted) {
@@ -209,18 +220,16 @@ class MediaDecoderJob {
   // Called when the decoder is completely drained and is ready to be released.
   void OnDecoderDrained();
 
-  // Creates |media_codec_bridge_| for decoding purpose. Returns true if it is
-  // created, or false otherwise.
-  bool CreateMediaCodecBridge();
-
-  // Called when an access unit is consumed by the decoder. |is_config_change|
-  // indicates whether the current access unit is a config change. If it is
-  // true, the next access unit is guarateed to be an I-frame.
-  virtual void CurrentDataConsumed(bool is_config_change) {}
+  // Creates |media_codec_bridge_| for decoding purpose.
+  // Returns STATUS_SUCCESS on success, or STATUS_FAILURE on failure, or
+  // STATUS_KEY_FRAME_REQUIRED if a browser seek is required.
+  MediaDecoderJobStatus CreateMediaCodecBridge();
 
   // Implemented by the child class to create |media_codec_bridge_| for a
-  // particular stream. Returns true if it is created, or false otherwise.
-  virtual bool CreateMediaCodecBridgeInternal() = 0;
+  // particular stream.
+  // Returns STATUS_SUCCESS on success, or STATUS_FAILURE on failure, or
+  // STATUS_KEY_FRAME_REQUIRED if a browser seek is required.
+  virtual MediaDecoderJobStatus CreateMediaCodecBridgeInternal() = 0;
 
   // Returns true if the |configs| doesn't match the current demuxer configs
   // the decoder job has.