media: Add unittest for MojoRenderer{Impl|Service}

media/renderers/renderer_impl_unittest.cc

Index: media/renderers/renderer_impl_unittest.cc
diff --git a/media/renderers/renderer_impl_unittest.cc b/media/renderers/renderer_impl_unittest.cc
index 4c901f712ab4078a2a9a3d20aaa58f67f5674a55..97900551f4d455206f28337f704e08a48d8d1928 100644
--- a/media/renderers/renderer_impl_unittest.cc
+++ b/media/renderers/renderer_impl_unittest.cc
@@ -68,8 +68,8 @@ class RendererImplTest : public ::testing::Test {
         video_renderer_client_(nullptr),
         audio_renderer_client_(nullptr),
         initialization_status_(PIPELINE_OK) {
-    // SetDemuxerExpectations() adds overriding expectations for expected
-    // non-NULL streams.
+    // CreateAudioStream() and CreateVideoStream() overrides expectations for
+    // expected non-NULL streams.
     DemuxerStream* null_pointer = NULL;
     EXPECT_CALL(*demuxer_, GetStream(_))
         .WillRepeatedly(Return(null_pointer));