Paint first frame faster, don't crash with no frames during EOS.

media/base/null_video_sink.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 "media/base/null_video_sink.h"
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 71 matching lines @@
       delay += interval_ * (-delay / interval_ + 1);
     current_render_time_ = now + delay;
     last_now_ = now;
   }
 
   task_runner_->PostDelayedTask(FROM_HERE, cancelable_worker_.callback(),
                                 delay);
 }
 
 void NullVideoSink::PaintSingleFrame(const scoped_refptr<VideoFrame>& frame) {
+  if (frame == last_frame_)
+    return;
+  last_frame_ = frame;
   new_frame_cb_.Run(frame);
 }
 
 }  // namespace media