Ignore sink start attempts when no frames are present.

media/renderers/video_renderer_impl_unittest.cc

 // Copyright 2013 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 <stdint.h>
 
 #include <memory>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 321 matching lines @@
     {
       SCOPED_TRACE("Waiting for BUFFERING_HAVE_NOTHING");
       WaitableMessageLoopEvent event;
       EXPECT_CALL(mock_cb_, BufferingStateChange(BUFFERING_HAVE_NOTHING))
           .WillOnce(RunClosure(event.GetClosure()));
       AdvanceTimeInMs(30);
       event.RunAndWait();
       Mock::VerifyAndClearExpectations(&mock_cb_);
     }
 
+    // Simulate delayed buffering state callbacks.
+    renderer_->OnTimeStateChanged(false);
+    renderer_->OnTimeStateChanged(true);
+
     // Receiving end of stream should signal having enough.
     {
       SCOPED_TRACE("Waiting for BUFFERING_HAVE_ENOUGH");
       WaitableMessageLoopEvent event;
       EXPECT_CALL(mock_cb_, BufferingStateChange(BUFFERING_HAVE_ENOUGH))
           .WillOnce(RunClosure(event.GetClosure()));
       SatisfyPendingReadWithEndOfStream();
       event.RunAndWait();
     }
 
@@ skipping 542 matching lines @@
   QueueFrames("0 10 20 30");
   StartPlayingFrom(0);
   Flush();
   ASSERT_EQ(1u, frame_ready_cbs_.size());
   // This frame will be discarded.
   frame_ready_cbs_.front().Run();
   Destroy();
 }
 
 }  // namespace media