Clear VideoRendererBase::current_frame_ when stopped.

I previously assumed that PipelineImpl would go through a clean Pause/Flush/Stop on an error but it turns out that Stop() can be called at anytime. Fortunately a DCHECK() would catch this condition and was easily triggerable using the test case attached in bug 100434.

Review URL: http://codereview.chromium.org/8561019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@110778 0039d316-1c4b-4281-b951-d872f2087c98

media/filters/video_renderer_base.cc

@@ -477,6 +477,7 @@ void VideoRendererBase::DoStopOrError_Locked() {
   DCHECK(!pending_paint_);
   DCHECK(!pending_paint_with_last_available_);
   lock_.AssertAcquired();
+  current_frame_ = NULL;
   last_available_frame_ = NULL;
   DCHECK(!pending_read_);
 }

media/filters/video_renderer_base_unittest.cc

@@ -379,6 +379,13 @@ TEST_F(VideoRendererBaseTest, GetCurrentFrame_Shutdown) {
   ExpectCurrentFrame(false);
 }
 
+// Stop() is called immediately during an error.
+TEST_F(VideoRendererBaseTest, GetCurrentFrame_Error) {
+  Initialize();
+  Stop();
+  ExpectCurrentFrame(false);
+}
+
 // Verify that shutdown can only proceed after we return the current frame.
 TEST_F(VideoRendererBaseTest, Shutdown_DuringPaint) {
   Initialize();