Fix MSE GC, make it less aggressive, more spec-compliant

media/filters/source_buffer_range.cc

 // Copyright 2014 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.
 
 #include "media/filters/source_buffer_range.h"
 
 #include <algorithm>
 
 namespace media {
 
@@ skipping 328 matching lines @@
 
     bytes_removed += gop_size;
   }
   if (bytes_removed > 0) {
     *removal_end_timestamp = gop_itr == keyframe_map_.end() ?
         GetBufferedEndTimestamp() : gop_itr->first;
   }
   return bytes_removed;
 }
 
+bool SourceBufferRange::FirstGOPEarlierThanMediaTime(
+    DecodeTimestamp media_time) const {
+  if (keyframe_map_.size() == 1u)
+    return (GetEndTimestamp() < media_time);
+
+  KeyframeMap::const_iterator second_gop = keyframe_map_.begin();
+  ++second_gop;
+  return second_gop->first <= media_time;
+}
+
 bool SourceBufferRange::FirstGOPContainsNextBufferPosition() const {
   if (!HasNextBufferPosition())
     return false;
 
   // If there is only one GOP, it must contain the next buffer position.
   if (keyframe_map_.size() == 1u)
     return true;
 
   KeyframeMap::const_iterator second_gop = keyframe_map_.begin();
   ++second_gop;
@@ skipping 255 matching lines @@
     }
 
     if (buffer->timestamp() + buffer->duration() <= start.ToPresentationTime())
       continue;
     buffers->push_back(buffer);
   }
   return previous_size < buffers->size();
 }
 
 }  // namespace media