Let Contraints Controll Mute/Unmute Audio Local Playback For Desktop Sharing

third_party/WebKit/Source/modules/mediastream/MediaConstraintsImpl.cpp

Index: third_party/WebKit/Source/modules/mediastream/MediaConstraintsImpl.cpp
diff --git a/third_party/WebKit/Source/modules/mediastream/MediaConstraintsImpl.cpp b/third_party/WebKit/Source/modules/mediastream/MediaConstraintsImpl.cpp
index 56c542d99bb0fa2d43524cb05623ef93976c2a78..6c33f10f85aa7349f9ff613987ccefd8a3a98ede 100644
--- a/third_party/WebKit/Source/modules/mediastream/MediaConstraintsImpl.cpp
+++ b/third_party/WebKit/Source/modules/mediastream/MediaConstraintsImpl.cpp
@@ -91,6 +91,7 @@ const char kMediaStreamAudioHotword[] = "googHotword";
 // TODO(hta): googHotword should go away. https://crbug.com/577627
 // From content/renderer/media/media_stream_audio_processor_options.cc
 const char kEchoCancellation[] = "echoCancellation";
+const char kGoogDisableLocalEcho[] = "googDisableLocalEcho";

[Mike West, 2016/09/27 08:03:41]

Is this web-exposed? That is, does a developer type this into JavaScript, or is
this just an internal name?

If it's web-exposed, then the name makes me sad (we should not be shipping new,
vendor-prefixed APIs), and there are no tests.

If it's not web-exposed, then I'm less concerned about the name, but I still
don't see any tests. You suggested that the implementation is in another CL: are
the tests there too?

[qiangchen, 2016/09/27 16:16:47]

It is web exposed. But it is not an API function name, just an entry in audio
constraint. 

For example:
getUserMedia({audio: {googDisableLocalEcho: true}, ......})

We want to give the developer a freedom to override default behavior and choose
whether stop local playback or not during sharing. But we did not find there is
such a parameter defined in W3C. If this is not allowed, then we have to give up
this CL.

We do have tests for the real functionality. But those tests have no idea of
googDisableLocalEcho, and in those tests we pass the bool parameter directly
into the class processing audio stream, and then we test whether it behaves as
expected. 

For here, I think the test you mean is a test that verifies that we can pass
googDisableLocalEcho from Javascript to the audio stream generating class,
right?

[Avi (use Gerrit), 2016/09/27 16:20:34]

Waaaaaait. I see lots of "googXXXX" constants in this file, around this line.

Are *all* of them web-exposed?

[qiangchen, 2016/09/27 16:32:49]

Yes. You can search them on google, and you will find the result is the
discussion of their usage. And the way to use them is much the same as 
getUserMedia({audio: {googXXXX: <value>}} ......)

 const char kGoogEchoCancellation[] = "googEchoCancellation";
 const char kGoogExperimentalEchoCancellation[] = "googEchoCancellation2";
 const char kGoogAutoGainControl[] = "googAutoGainControl";
@@ -294,6 +295,8 @@ static void parseOldStyleNames(ExecutionContext* context, const Vector<NameValue
             // represented as an enum, and cause type errors.
             // https://crbug.com/576582
             result.mediaStreamSource.setExact(constraint.m_value);
+        } else if (constraint.m_name.equals(kGoogDisableLocalEcho)) {
+            result.googDisableLocalEcho.setExact(toBoolean(constraint.m_value));
         } else if (constraint.m_name.equals(kMediaStreamSourceId)
             || constraint.m_name.equals(kMediaStreamSourceInfoId)) {
             result.deviceId.setExact(constraint.m_value);