media: In low delay mode, do not accumulate frames earlier than the start time.

media/renderers/video_renderer_impl_unittest.cc

Index: media/renderers/video_renderer_impl_unittest.cc
diff --git a/media/renderers/video_renderer_impl_unittest.cc b/media/renderers/video_renderer_impl_unittest.cc
index ba5d80f9672bd27a92bd15805eb0afd358b481f0..794fb01988739f3302dce3ded578cbcae1663a68 100644
--- a/media/renderers/video_renderer_impl_unittest.cc
+++ b/media/renderers/video_renderer_impl_unittest.cc
@@ -46,7 +46,8 @@ MATCHER_P(HasTimestamp, ms, "") {
   return arg->timestamp().InMilliseconds() == ms;
 }
 
-class VideoRendererImplTest : public testing::TestWithParam<bool> {
+class VideoRendererImplTest
+    : public testing::TestWithParam<bool /* new_video_renderer */> {
  public:
   VideoRendererImplTest()
       : tick_clock_(new base::SimpleTestTickClock()),
@@ -487,28 +488,29 @@ TEST_P(VideoRendererImplTest, StartPlayingFrom_RightAfter) {
 }
 
 TEST_P(VideoRendererImplTest, StartPlayingFrom_LowDelay) {
-  // In low-delay mode only one frame is required to finish preroll.
+  // In low-delay mode only one frame is required to finish preroll. But frames
+  // prior to the start time will not be used.
   InitializeWithLowDelay(true);
-  QueueFrames("0");
+  QueueFrames("0 10");
 
+  EXPECT_CALL(mock_cb_, FrameReceived(HasTimestamp(10)));
   // Expect some amount of have enough/nothing due to only requiring one frame.
-  EXPECT_CALL(mock_cb_, FrameReceived(HasTimestamp(0)));
   EXPECT_CALL(mock_cb_, BufferingStateChange(BUFFERING_HAVE_ENOUGH))
       .Times(AnyNumber());
   EXPECT_CALL(mock_cb_, BufferingStateChange(BUFFERING_HAVE_NOTHING))
       .Times(AnyNumber());

[xhwang, 2015/07/21 20:30:26]

When using the old rendering path, we declare HAVE_NOTHING whenever we run out
of frame, which could be pretty common in low delay mode in tests. In real life
this could also happen. Maybe we should have some grace period to declare
HAVE_NOTHING in low delay mode.

Or, when are we gonna drop old rendering path altogether? It's such a pain to
keep them both in our code...

[DaleCurtis, 2015/07/21 21:16:50]

I was planning to delete the old path this week as soon as I can find time :)

-  StartPlayingFrom(0);
+  StartPlayingFrom(10);
 
-  QueueFrames("10");
+  QueueFrames("20");
   SatisfyPendingRead();
 
   renderer_->OnTimeStateChanged(true);
   time_source_.StartTicking();
 
   WaitableMessageLoopEvent event;
-  EXPECT_CALL(mock_cb_, FrameReceived(HasTimestamp(10)))
+  EXPECT_CALL(mock_cb_, FrameReceived(HasTimestamp(20)))
       .WillOnce(RunClosure(event.GetClosure()));
-  AdvanceTimeInMs(10);
+  AdvanceTimeInMs(20);
   event.RunAndWait();
 
   Destroy();