Introduce audio/video BufferingState to Pipeline.

media/base/pipeline.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_BASE_PIPELINE_H_
 #define MEDIA_BASE_PIPELINE_H_
 
 #include <string>
 
 #include "base/gtest_prod_util.h"
 #include "base/synchronization/condition_variable.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/default_tick_clock.h"
 #include "media/base/audio_renderer.h"
+#include "media/base/buffering_state.h"
 #include "media/base/demuxer.h"
 #include "media/base/media_export.h"
 #include "media/base/pipeline_status.h"
 #include "media/base/ranges.h"
 #include "media/base/serial_runner.h"
 #include "ui/gfx/size.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 class TimeDelta;
@@ skipping 25 matching lines @@
 // machine to perform asynchronous initialization, pausing, seeking and playing.
 //
 // Here's a state diagram that describes the lifetime of this object.
 //
 //   [ *Created ]                       [ Any State ]
 //         | Start()                         | Stop() / SetError()
 //         V                                 V
 //   [ InitXXX (for each filter) ]      [ Stopping ]
 //         |                                 |
 //         V                                 V
-//   [ InitPreroll ]                    [ Stopped ]
+//   [ InitPrerolling ]                 [ Stopped ]
 //         |
 //         V
-//   [ Starting ] <-- [ Seeking ]
+//   [ Playing ] <-- [ Seeking ]
 //         |               ^
-//         V               |
-//   [ Started ] ----------'
-//                 Seek()
+//         `---------------'
+//              Seek()
 //
 // Initialization is a series of state transitions from "Created" through each
 // filter initialization state.  When all filter initialization states have
 // completed, we are implicitly in a "Paused" state.  At that point we simulate
 // a Seek() to the beginning of the media to give filters a chance to preroll.
 // From then on the normal Seek() transitions are carried out and we start
 // playing the media.
 //
 // If any error ever happens, this object will transition to the "Error" state
 // from any state. If Stop() is ever called, this object will transition to
@@ skipping 108 matching lines @@
   friend class MediaLog;
 
   // Pipeline states, as described above.
   enum State {
     kCreated,
     kInitDemuxer,
     kInitAudioRenderer,
     kInitVideoRenderer,
     kInitPrerolling,
     kSeeking,
-    kStarting,
-    kStarted,
+    kPlaying,
     kStopping,
     kStopped,
   };
 
   // Updates |state_|. All state transitions should use this call.
   void SetState(State next_state);
 
   static const char* GetStateString(State state);
   State GetNextState() const;
 
@@ skipping 89 matching lines @@
   void DoInitialPreroll(const PipelineStatusCB& done_cb);
 
   // Initiates an asynchronous pause-flush-seek-preroll call sequence
   // executing |done_cb| with the final status when completed.
   //
   // TODO(scherkus): Prerolling should be separate from seeking so we can report
   // finer grained ready states (HAVE_CURRENT_DATA vs. HAVE_FUTURE_DATA)
   // indepentent from seeking.
   void DoSeek(base::TimeDelta seek_timestamp, const PipelineStatusCB& done_cb);
 
-  // Updates playback rate and volume and initiates an asynchronous play call
-  // sequence executing |done_cb| with the final status when completed.
-  void DoPlay(const PipelineStatusCB& done_cb);
-
   // Initiates an asynchronous pause-flush-stop call sequence executing
   // |done_cb| when completed.
   void DoStop(const PipelineStatusCB& done_cb);
   void OnStopCompleted(PipelineStatus status);
 
   void OnAudioUnderflow();
 
+  // Collection of callback methods and helpers for tracking changes in
+  // buffering state and transition from paused/underflow states and playing
+  // states.
+  //
+  // While in the kPlaying state:
+  //   - A waiting to non-waiting transition indicates preroll has completed
+  //     and StartPlayback() should be called
+  //   - A non-waiting to waiting transition indicates underflow has occurred
+  //     and StartWaitingForEnoughData() should be called
+  void BufferingStateChanged(BufferingState* buffering_state,
+                             BufferingState new_buffering_state);
+  bool WaitingForEnoughData() const;
+  void StartWaitingForEnoughData();
+  void StartPlayback();
+
   void StartClockIfWaitingForTimeUpdate_Locked();
 
   // Task runner used to execute pipeline tasks.
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
   // MediaLog to which to log events.
   scoped_refptr<MediaLog> media_log_;
 
   // Lock used to serialize access for the following data members.
   mutable base::Lock lock_;
@@ skipping 41 matching lines @@
   // |task_runner_|.
 
   // Member that tracks the current state.
   State state_;
 
   // Whether we've received the audio/video/text ended events.
   bool audio_ended_;
   bool video_ended_;
   bool text_ended_;
 
+  BufferingState audio_buffering_state_;
+  BufferingState video_buffering_state_;
+
   // Temporary callback used for Start() and Seek().
   PipelineStatusCB seek_cb_;
 
   // Temporary callback used for Stop().
   base::Closure stop_cb_;
 
   // Permanent callbacks passed in via Start().
   base::Closure ended_cb_;
   PipelineStatusCB error_cb_;
   PipelineMetadataCB metadata_cb_;
@@ skipping 21 matching lines @@
   scoped_ptr<SerialRunner> pending_callbacks_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(Pipeline);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_PIPELINE_H_