Enable platform echo cancellation through the AudioRecord path.

content/renderer/media/media_stream_dependency_factory.cc

Index: content/renderer/media/media_stream_dependency_factory.cc
diff --git a/content/renderer/media/media_stream_dependency_factory.cc b/content/renderer/media/media_stream_dependency_factory.cc
index 6172e06a8e31da352c32b056fc1cf6585ef2dcc6..8da7b14cb7120cc0a1d05b5b84c2414896d433fa 100644
--- a/content/renderer/media/media_stream_dependency_factory.cc
+++ b/content/renderer/media/media_stream_dependency_factory.cc
@@ -78,6 +78,15 @@ struct {
     webrtc::MediaConstraintsInterface::kValueTrue },
 };
 
+// Map of corresponding media constraints and platform effects.
+struct {
+  const char* constraint;
+  const media::AudioParameters::PlatformEffectsMask effect;
+} const kConstraintEffectMap[] = {
+  { webrtc::MediaConstraintsInterface::kEchoCancellation,
+    media::AudioParameters::ECHO_CANCELLER},
+};
+
 // Merge |constraints| with |kDefaultAudioConstraints|. For any key which exists
 // in both, the value from |constraints| is maintained, including its
 // mandatory/optional status. New values from |kDefaultAudioConstraints| will
@@ -323,7 +332,36 @@ void MediaStreamDependencyFactory::CreateNativeMediaSources(
 
     // TODO(xians): Create a new capturer for difference microphones when we
     // support multiple microphones. See issue crbug/262117 .
-    const StreamDeviceInfo device_info = source_data->device_info();
+    StreamDeviceInfo device_info = source_data->device_info();
+    RTCMediaConstraints constraints = native_audio_constraints;
+
+    // If any platform effects are available, check them against the
+    // constraints. Disable effects to match false constraints, but if a
+    // constraint is true, set the constraint to false to later disable the
+    // software effect.
+    int effects = device_info.device.input.effects;
+    if (effects != media::AudioParameters::NO_EFFECTS) {
+      for (size_t i = 0; i < ARRAYSIZE_UNSAFE(kConstraintEffectMap); ++i) {
+        bool value;
+        if (!webrtc::FindConstraint(&constraints,
+                kConstraintEffectMap[i].constraint, &value, NULL) || !value) {
+          // If the constraint is false, or does not exist, disable the platform
+          // effect.
+          effects &= ~kConstraintEffectMap[i].effect;
+          DVLOG(1) << "Disabling constraint: "
+                   << kConstraintEffectMap[i].constraint;
+        } else if (effects & kConstraintEffectMap[i].effect) {
+          // If the constraint is true, leave the platform effect enabled, and
+          // set the constraint to false to later disable the software effect.
+          constraints.AddMandatory(kConstraintEffectMap[i].constraint,
+              webrtc::MediaConstraintsInterface::kValueFalse, true);
+          DVLOG(1) << "Disabling platform effect: "
+                   << kConstraintEffectMap[i].constraint;
+        }
+      }
+      device_info.device.input.effects = effects;
+    }
+
     scoped_refptr<WebRtcAudioCapturer> capturer(
         MaybeCreateAudioCapturer(render_view_id, device_info));
     if (!capturer.get()) {
@@ -341,7 +379,7 @@ void MediaStreamDependencyFactory::CreateNativeMediaSources(
     // Creates a LocalAudioSource object which holds audio options.
     // TODO(xians): The option should apply to the track instead of the source.
     source_data->SetLocalAudioSource(
-        CreateLocalAudioSource(&native_audio_constraints).get());
+        CreateLocalAudioSource(&constraints).get());
     source_observer->AddSource(source_data->local_audio_source());
   }
 
@@ -910,7 +948,8 @@ MediaStreamDependencyFactory::MaybeCreateAudioCapturer(
           device_info.session_id,
           device_info.device.id,
           device_info.device.matched_output.sample_rate,
-          device_info.device.matched_output.frames_per_buffer)) {
+          device_info.device.matched_output.frames_per_buffer,
+          device_info.device.input.effects)) {
     return NULL;
   }