alsa_output: Drain and pause pcm when stopping.

media/audio/linux/alsa_output_unittest.cc

Index: media/audio/linux/alsa_output_unittest.cc
diff --git a/media/audio/linux/alsa_output_unittest.cc b/media/audio/linux/alsa_output_unittest.cc
index 4b314cebe5d28421a8edb9e50859ee583cb9db0c..5f9b4e77ba22dd3668e94857fa295da6837ec356 100644
--- a/media/audio/linux/alsa_output_unittest.cc
+++ b/media/audio/linux/alsa_output_unittest.cc
@@ -43,6 +43,7 @@ class MockAlsaWrapper : public AlsaWrapper {
                             snd_pcm_stream_t stream, int mode));
   MOCK_METHOD1(PcmClose, int(snd_pcm_t* handle));
   MOCK_METHOD1(PcmPrepare, int(snd_pcm_t* handle));
+  MOCK_METHOD1(PcmDrain, int(snd_pcm_t* handle));
   MOCK_METHOD1(PcmDrop, int(snd_pcm_t* handle));
   MOCK_METHOD2(PcmDelay, int(snd_pcm_t* handle, snd_pcm_sframes_t* delay));
   MOCK_METHOD3(PcmWritei, snd_pcm_sframes_t(snd_pcm_t* handle,
@@ -458,6 +459,10 @@ TEST_F(AlsaPcmOutputStreamTest, StartStop) {
   test_stream->Start(&mock_callback);
   message_loop_.RunAllPending();
 
+  EXPECT_CALL(mock_alsa_wrapper_, PcmDrain(kFakeHandle))
+      .WillOnce(Return(0));
+  test_stream->Stop();
+
   EXPECT_CALL(mock_alsa_wrapper_, PcmClose(kFakeHandle))
       .WillOnce(Return(0));
   EXPECT_CALL(mock_alsa_wrapper_, PcmName(kFakeHandle))