VP8Decoder: Drop references to reference frames earlier.

content/common/gpu/media/v4l2_slice_video_decode_accelerator.cc

 // Copyright 2015 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 <fcntl.h>
 #include <linux/videodev2.h>
 #include <poll.h>
 #include <sys/eventfd.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
@@ skipping 1247 matching lines @@
 
 void V4L2SliceVideoDecodeAccelerator::FinishSurfaceSetChangeIfNeeded() {
   DVLOGF(2);
   DCHECK(decoder_thread_proxy_->BelongsToCurrentThread());
 
   if (!surface_set_change_pending_ || !surfaces_at_device_.empty())
     return;
 
   DCHECK_EQ(state_, kIdle);
   DCHECK(decoder_display_queue_.empty());
+  // All output buffers should've been returned from decoder and device by now.
+  DCHECK_EQ(free_output_buffers_.size(), output_buffer_map_.size());
 
   // Keep input queue running while we switch outputs.
   if (!StopDevicePoll(true)) {
     NOTIFY_ERROR(PLATFORM_FAILURE);
     return;
   }
 
   // This will return only once all buffers are dismissed and destroyed.
   // This does not wait until they are displayed however, as display retains
   // references to the buffers bound to textures and will release them
@@ skipping 1180 matching lines @@
   DCHECK_GT(picture_clearing_count_, 0);
   picture_clearing_count_--;
   SendPictureReady();
 }
 
 bool V4L2SliceVideoDecodeAccelerator::CanDecodeOnIOThread() {
   return true;
 }
 
 }  // namespace content