Rename media::Clock to media::TimeDeltaInterpolator and update API.

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"
@@ skipping 10 matching lines @@
 #include "media/base/serial_runner.h"
 #include "ui/gfx/size.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 class TimeDelta;
 }
 
 namespace media {
 
-class Clock;
 class FilterCollection;
 class MediaLog;
 class TextRenderer;
 class TextTrackConfig;
+class TimeDeltaInterpolator;
 class VideoRenderer;
 
 // Metadata describing a pipeline once it has been initialized.
 struct PipelineMetadata {
   PipelineMetadata() : has_audio(false), has_video(false) {}
 
   bool has_audio;
   bool has_video;
   gfx::Size natural_size;
   base::Time timeline_offset;
@@ skipping 126 matching lines @@
   // Return true if loading progress has been made since the last time this
   // method was called.
   bool DidLoadingProgress();
 
   // Gets the current pipeline statistics.
   PipelineStatistics GetStatistics() const;
 
   void set_underflow_disabled_for_testing(bool disabled) {
     underflow_disabled_for_testing_ = disabled;
   }
-  void SetClockForTesting(Clock* clock);
+  void SetTimeDeltaInterpolatorForTesting(TimeDeltaInterpolator* interpolator);
   void SetErrorForTesting(PipelineStatus status);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(PipelineTest, GetBufferedTimeRanges);
   FRIEND_TEST_ALL_PREFIXES(PipelineTest, EndedCallback);
   FRIEND_TEST_ALL_PREFIXES(PipelineTest, AudioStreamShorterThanVideo);
   friend class MediaLog;
 
   // Pipeline states, as described above.
   enum State {
@@ skipping 122 matching lines @@
   //   - 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 PausePlayback() should be called
   void BufferingStateChanged(BufferingState* buffering_state,
                              BufferingState new_buffering_state);
   bool WaitingForEnoughData() const;
   void PausePlayback();
   void StartPlayback();
 
   void PauseClockAndStopRendering_Locked();

[scherkus (not reviewing), 2014/07/08 22:36:49]

note to self: I need to update these method names

   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 14 matching lines @@
   float volume_;
 
   // Current playback rate (>= 0.0f).  This value is set immediately via
   // SetPlaybackRate() and a task is dispatched on the task runner to notify
   // the filters.
   float playback_rate_;
 
   // Current duration as reported by |demuxer_|.
   base::TimeDelta duration_;
 
-  // base::TickClock used by |clock_|.
+  // base::TickClock used by |interpolator_|.
   base::DefaultTickClock default_tick_clock_;
 
-  // Reference clock.  Keeps track of current playback time.  Uses system
-  // clock and linear interpolation, but can have its time manually set
-  // by filters.
-  scoped_ptr<Clock> clock_;
+  // Tracks the most recent media time update and provides interpolated values
+  // as playback progresses.
+  scoped_ptr<TimeDeltaInterpolator> interpolator_;
 
-  enum ClockState {
-    // Audio (if present) is not rendering. Clock isn't playing.
-    CLOCK_PAUSED,
+  enum InterpolationState {

[acolwell GONE FROM CHROMIUM, 2014/07/09 00:42:46]

It seems weird that we are keeping track of this state outside of the
interpolator. It seems like we are missing a call on the interpolator_ object so
that we can differentiate the audio & video case inside that object.

[scherkus (not reviewing), 2014/07/09 01:54:32]

Yeah I have some future CLs in mind to help clean more of this up. Going to hold
off for now.

+    // Audio (if present) is not rendering. Time isn't being interpolated.
+    INTERPOLATION_STOPPED,
 
-    // Audio (if present) is rendering. Clock isn't playing.
-    CLOCK_WAITING_FOR_AUDIO_TIME_UPDATE,
+    // Audio (if present) is rendering. Time isn't being interpolated.
+    INTERPOLATION_WAITING_FOR_AUDIO_TIME_UPDATE,
 
-    // Audio (if present) is rendering. Clock is playing.
-    CLOCK_PLAYING,
+    // Audio (if present) is rendering. Time is being interpolated.
+    INTERPOLATION_STARTED,
   };
 
-  ClockState clock_state_;
+  InterpolationState interpolation_state_;
 
   // Status of the pipeline.  Initialized to PIPELINE_OK which indicates that
   // the pipeline is operating correctly. Any other value indicates that the
   // pipeline is stopped or is stopping.  Clients can call the Stop() method to
   // reset the pipeline state, and restore this to PIPELINE_OK.
   PipelineStatus status_;
 
   // The following data members are only accessed by tasks posted to
   // |task_runner_|.
 
@@ skipping 43 matching lines @@
   bool underflow_disabled_for_testing_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(Pipeline);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_PIPELINE_H_