Fix DCHECK when track status changes in non-playing state

media/test/pipeline_integration_test.cc

 // Copyright (c) 2012 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 <stddef.h>
 #include <stdint.h>
 
 #include <memory>
 #include <utility>
 
@@ skipping 1003 matching lines @@
 
   // Restart playback from 500ms position.
   ASSERT_TRUE(Seek(k500ms));
   Play();
   ASSERT_TRUE(WaitUntilOnEnded());
 
   // Verify that video has been rendered after being enabled.
   EXPECT_HASH_EQ("fd59357dfd9c144ab4fb8181b2de32c3", GetVideoHash());
 }
 
+TEST_F(PipelineIntegrationTest, TrackStatusChangesAfterPipelineEnded) {
+  ASSERT_EQ(PIPELINE_OK, Start("bear-320x240.webm", kHashed));
+  Play();
+  ASSERT_TRUE(WaitUntilOnEnded());

[chcunningham, 2016/08/24 22:16:53]

Is the expectation that waiting until ended will cause the renderer to be
removed due to suspend? IIRC it takes a few seconds for suspend to kick in --
you may not be reliably testing the DCHECK case

[servolk, 2016/08/24 22:46:32]

No, we don't need suspend to happen. After pipeline is ended it transitions into
the kStopped state and that is enough to test that the updated DCHECK in the
pipeline_impl.cc is no longer triggered.

[chcunningham, 2016/08/25 20:45:54]

I don't think this transition to stopped is happening. I patched your change and
added logs to pipeline_impl just before your dcheck:

OnEnabledAudioTracksChanged shared_state_.renderer:0x381e5dca8e20 state_:3
OnEnabledAudioTracksChanged shared_state_.renderer:0x381e5dca8e20 state_:3
OnSelectedVideoTrackChanged shared_state_.renderer:0x381e5dca8e20 state_:3
OnSelectedVideoTrackChanged shared_state_.renderer:0x381e5dca8e20 state_:3

So the state is always 3 (playing) and the renderer pointer is always non-null.
So this test passes before and after your changes to the DCHECK.

+  std::vector<MediaTrack::Id> track_ids;
+  // Disable audio track.
+  pipeline_->OnEnabledAudioTracksChanged(track_ids);
+  // Re-enable audio track.
+  track_ids.push_back("2");
+  pipeline_->OnEnabledAudioTracksChanged(track_ids);
+  // Disable video track.
+  track_ids.clear();
+  pipeline_->OnSelectedVideoTrackChanged(track_ids);
+  // Re-enable video track.
+  track_ids.push_back("1");
+  pipeline_->OnSelectedVideoTrackChanged(track_ids);
+}
+
 TEST_F(PipelineIntegrationTest,
        MAYBE_CLOCKLESS(BasicPlaybackOpusOggTrimmingHashed)) {
   ASSERT_EQ(PIPELINE_OK,
             Start("opus-trimming-test.webm", kHashed | kClockless));
 
   Play();
 
   ASSERT_TRUE(WaitUntilOnEnded());
   EXPECT_HASH_EQ(kOpusEndTrimmingHash_1, GetAudioHash());
 
@@ skipping 1364 matching lines @@
 
 TEST_F(PipelineIntegrationTest, BasicPlaybackPositiveStartTime) {
   ASSERT_EQ(PIPELINE_OK, Start("nonzero-start-time.webm"));
   Play();
   ASSERT_TRUE(WaitUntilOnEnded());
   ASSERT_EQ(base::TimeDelta::FromMicroseconds(396000),
             demuxer_->GetStartTime());
 }
 
 }  // namespace media