Implement evictFrames() to support MSE's coded frame eviction algorithm.

media/filters/source_buffer_stream.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.
 
 // SourceBufferStream is a data structure that stores media Buffers in ranges.
 // Buffers can be appended out of presentation order. Buffers are retrieved by
 // seeking to the desired start point and calling GetNextBuffer(). Buffers are
 // returned in sequential presentation order.
 
 #ifndef MEDIA_FILTERS_SOURCE_BUFFER_STREAM_H_
@@ skipping 71 matching lines @@
   // Removes buffers between |start| and |end| according to the steps
   // in the "Coded Frame Removal Algorithm" in the Media Source
   // Extensions Spec.
   // https://dvcs.w3.org/hg/html-media/raw-file/default/media-source/media-source.html#sourcebuffer-coded-frame-removal
   //
   // |duration| is the current duration of the presentation. It is
   // required by the computation outlined in the spec.
   void Remove(base::TimeDelta start, base::TimeDelta end,
               base::TimeDelta duration);
 
+  // Frees up space if the SourceBufferStream is taking up too much memory.
+  bool GarbageCollectIfNeeded();
+
   // Changes the SourceBufferStream's state so that it will start returning
   // buffers starting from the closest keyframe before |timestamp|.
   void Seek(base::TimeDelta timestamp);
 
   // Returns true if the SourceBufferStream has seeked to a time without
   // buffered data and is waiting for more data to be appended.
   bool IsSeekPending() const;
 
   // Notifies the SourceBufferStream that the media duration has been changed to
   // |duration| so it should drop any data past that point.
@@ skipping 40 matching lines @@
   // yet.
   base::TimeDelta GetMaxInterbufferDistance() const;
 
   void set_memory_limit(int memory_limit) {
     memory_limit_ = memory_limit;
   }
 
  private:
   friend class SourceBufferStreamTest;
 
-  // Frees up space if the SourceBufferStream is taking up too much memory.
-  void GarbageCollectIfNeeded();
-
   // Attempts to delete approximately |total_bytes_to_free| amount of data
   // |ranges_|, starting at the front of |ranges_| and moving linearly forward
   // through the buffers. Deletes starting from the back if |reverse_direction|
   // is true. Returns the number of bytes freed.
   int FreeBuffers(int total_bytes_to_free, bool reverse_direction);
 
   // Attempts to delete approximately |total_bytes_to_free| amount of data from
   // |ranges_|, starting after the last appended buffer before the current
   // playback position.
   int FreeBuffersAfterLastAppended(int total_bytes_to_free);
@@ skipping 249 matching lines @@
 
   // Indicates that splice frame generation is enabled.
   const bool splice_frames_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(SourceBufferStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_SOURCE_BUFFER_STREAM_H_