Feed audio constraints over to WebRtcLocalAudioTrack

content/renderer/media/webrtc_local_audio_track.cc

Index: content/renderer/media/webrtc_local_audio_track.cc
diff --git a/content/renderer/media/webrtc_local_audio_track.cc b/content/renderer/media/webrtc_local_audio_track.cc
index cae6bfe8ba38bcd85a32f75cf6c6faaa6d1514e5..2dacc4b1bb5b6a069bd853fb4bedcfb8f8255be2 100644
--- a/content/renderer/media/webrtc_local_audio_track.cc
+++ b/content/renderer/media/webrtc_local_audio_track.cc
@@ -12,28 +12,74 @@ namespace content {
 
 static const char kAudioTrackKind[] = "audio";
 
+namespace {
+
+using webrtc::MediaConstraintsInterface;
+
+// This helper function checks if any audio constraints are set that require
+// audio processing to be applied.  Right now this is a big, single switch for
+// all of the properties, but in the future they'll be handled one by one.
+bool NeedsAudioProcessing(
+    const webrtc::MediaConstraintsInterface* constraints) {
+  if (!constraints)
+    return false;
+
+  static const char* kAudioProcessingProperties[] = {
+    MediaConstraintsInterface::kEchoCancellation,
+    MediaConstraintsInterface::kExperimentalEchoCancellation,
+    MediaConstraintsInterface::kAutoGainControl,
+    MediaConstraintsInterface::kExperimentalAutoGainControl,
+    MediaConstraintsInterface::kNoiseSuppression,
+    MediaConstraintsInterface::kHighpassFilter,
+  };
+
+  for (int i = 0; i < arraysize(kAudioProcessingProperties); ++i) {
+    bool value = false;
+    if (webrtc::FindConstraint(constraints, kAudioProcessingProperties[i],
+                               &value, NULL) &&
+        value) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+}  // namespace.
+
 scoped_refptr<WebRtcLocalAudioTrack> WebRtcLocalAudioTrack::Create(
     const std::string& id,
     const scoped_refptr<WebRtcAudioCapturer>& capturer,
-    webrtc::AudioSourceInterface* track_source) {
+    webrtc::AudioSourceInterface* track_source,
+    const webrtc::MediaConstraintsInterface* constraints) {
   talk_base::RefCountedObject<WebRtcLocalAudioTrack>* track =
       new talk_base::RefCountedObject<WebRtcLocalAudioTrack>(
-          id, capturer, track_source);
+          id, capturer, track_source, constraints);
   return track;
 }
 
 WebRtcLocalAudioTrack::WebRtcLocalAudioTrack(
     const std::string& label,
     const scoped_refptr<WebRtcAudioCapturer>& capturer,
-    webrtc::AudioSourceInterface* track_source)
+    webrtc::AudioSourceInterface* track_source,
+    const webrtc::MediaConstraintsInterface* constraints)
     : webrtc::MediaStreamTrack<webrtc::AudioTrackInterface>(label),
       capturer_(capturer),
       track_source_(track_source),
-      need_audio_processing_(!capturer->device_id().empty()) {
+      need_audio_processing_(NeedsAudioProcessing(constraints)) {

[tommi (sloooow) - chröme, 2013/08/26 08:18:36]

Henrik: Take a look at this line, see how it was and how it is now.

Shijing added support for "need_audio_processing_" but we hadn't hooked up the
constraints.  So, a workaround was to set needs_audio_processing_ to true for a
non-empty device id.  WebAudio's device id is always empty, so
needs_audio_processing_ would be set to false.  Now we actually check the
constraints.

[henrika (OOO until Aug 14), 2013/08/26 11:34:55]

Thanks for pointing out this key change.

   // The capturer with a valid device id is using microphone as source,
   // and APM (AudioProcessingModule) is turned on only for microphone data.
   DCHECK(capturer.get());
   DVLOG(1) << "WebRtcLocalAudioTrack::WebRtcLocalAudioTrack()";
+
+  // TODO(xians): Remove this workaround. It is currently here to maintain
+  // backwards compatibility with the previous implementations and apps where
+  // no constraints are specified for audio but we've still enabled audio
+  // processing.
+  if (!need_audio_processing_ && !capturer->device_id().empty()) {

[henrika (OOO until Aug 14), 2013/08/26 08:04:55]

What is a typical case when we can hit this part?

[tommi (sloooow) - chröme, 2013/08/26 08:18:36]

apprtc.appspot.com for instance.  No audio processing related constraints are
passed to the call to getUserMedia, yet previous versions of Chrome have had
audio processing enabled despite that.
This is here to not break the functionality as it currently is on beta and
stable but we need to decide if these constraints should be implicitly enabled
or not and if so, set the appropriate constraints if not already present.

[henrika (OOO until Aug 14), 2013/08/26 11:34:55]

OK.

+    DLOG(WARNING) << "Enabling audio processing despite lack of constraints.";
+    need_audio_processing_ = true;
+  }
 }
 
 WebRtcLocalAudioTrack::~WebRtcLocalAudioTrack() {