MediaStream tests need to call WebHeap::collectGarbage

content/renderer/media/webrtc_local_audio_track_unittest.cc

Index: content/renderer/media/webrtc_local_audio_track_unittest.cc
diff --git a/content/renderer/media/webrtc_local_audio_track_unittest.cc b/content/renderer/media/webrtc_local_audio_track_unittest.cc
index 20c462e15d3804f4c2b39bd99f9fe0b7f3971a9d..0bbd7a1260cfd143bfd0461998efa62e82bbc198 100644
--- a/content/renderer/media/webrtc_local_audio_track_unittest.cc
+++ b/content/renderer/media/webrtc_local_audio_track_unittest.cc
@@ -16,6 +16,7 @@
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/WebKit/public/platform/WebMediaConstraints.h"
+#include "third_party/WebKit/public/web/WebHeap.h"
 #include "third_party/libjingle/source/talk/app/webrtc/mediastreaminterface.h"
 
 using ::testing::_;
@@ -190,6 +191,11 @@ class WebRtcLocalAudioTrackTest : public ::testing::Test {
     capturer_->SetCapturerSourceForTesting(capturer_source_, params_);
   }
 
+  virtual void TearDown() OVERRIDE {
+    blink_source_.reset();

[haraken, 2014/09/09 04:51:16]

The reason we need to reset blink_source_ here is complicated.

The reset is needed to destruct capturer_source_ before destructing the
WebRtcLocalAudioTrackTest object. If we don't call the reset, the
capturer_source_ is destructed in a GC triggered after destructing the
WebRtcLocalAudioTrackTest object. This is too late because the testing system
complains that "the capturer_source_ was leaking when the
WebRtcLocalAudioTrackTest finished". Thus we need the reset.

The reason the capturer_source_ is not destructed soon is because the
WebRtcLocalAudioTrackTest object has a strong reference to the capturer_source_
as follows:

WebRtcLocalAudioTrackTest ==(part of object)==> WebMediaStreamSource
==(persistent handle)==> MediaStreamSource ==(OwnPtr)==> ExtraData ==(inherited
by)==> MediaStreamAudioSource ==(scoped_refptr)==> WebRtcAudioCapturer
==(scoped_refptr)==> MockCapturerSource.

Before oilpan, this long strong reference chain was broken promptly when the
WebRtcLocalAudioTrackTest gets destructed. On the other hand, after oilpan, the
chain is not broken until a next GC happens after the WebRtcLocalAudioTrackTest
gets destructed (if we don't call the explicit reset() in TearDown and
explicitly break the chain).

For the same reason, this CL adds a couple of reset() calls in TearDown(). (The
reset() calls in other tests are more complicated to explain why they are
needed. The chain is very long.)

+    blink::WebHeap::collectAllGarbage();
+  }
+
   media::AudioParameters params_;
   blink::WebMediaStreamSource blink_source_;
   scoped_refptr<MockCapturerSource> capturer_source_;