MSE - Fix crash caused by incorrect GC of GOP with next buffer position

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>
 
 #include "media/base/timestamp_constants.h"
 
@@ skipping 213 matching lines @@
 bool SourceBufferRange::TruncateAt(
     DecodeTimestamp timestamp, BufferQueue* removed_buffers,
     bool is_exclusive) {
   // Find the place in |buffers_| where we will begin deleting data.
   BufferQueue::iterator starting_point =
       GetBufferItrAt(timestamp, is_exclusive);
   return TruncateAt(starting_point, removed_buffers);
 }
 
 size_t SourceBufferRange::DeleteGOPFromFront(BufferQueue* deleted_buffers) {
+  DCHECK(!buffers_.empty());
   DCHECK(!FirstGOPContainsNextBufferPosition());
   DCHECK(deleted_buffers);
 
   int buffers_deleted = 0;
   size_t total_bytes_deleted = 0;
 
   KeyframeMap::iterator front = keyframe_map_.begin();
   DCHECK(front != keyframe_map_.end());
 
   // Delete the keyframe at the start of |keyframe_map_|.
@@ skipping 28 matching lines @@
 
   // Invalidate media segment start time if we've deleted the first buffer of
   // the range.
   if (buffers_deleted > 0)
     media_segment_start_time_ = kNoDecodeTimestamp();
 
   return total_bytes_deleted;
 }
 
 size_t SourceBufferRange::DeleteGOPFromBack(BufferQueue* deleted_buffers) {
+  DCHECK(!buffers_.empty());
   DCHECK(!LastGOPContainsNextBufferPosition());
   DCHECK(deleted_buffers);
 
   // Remove the last GOP's keyframe from the |keyframe_map_|.
   KeyframeMap::iterator back = keyframe_map_.end();
   DCHECK_GT(keyframe_map_.size(), 0u);
   --back;
 
   // The index of the first buffer in the last GOP is equal to the new size of
   // |buffers_| after that GOP is deleted.
@@ skipping 334 matching lines @@
     }
 
     if (buffer->timestamp() + buffer->duration() <= start.ToPresentationTime())
       continue;
     buffers->push_back(buffer);
   }
   return previous_size < buffers->size();
 }
 
 }  // namespace media