Include default communication devices in audio device enumerations. This removes heuristic that pic…

content/renderer/media/webrtc/peer_connection_dependency_factory.cc

Index: content/renderer/media/webrtc/peer_connection_dependency_factory.cc
diff --git a/content/renderer/media/webrtc/peer_connection_dependency_factory.cc b/content/renderer/media/webrtc/peer_connection_dependency_factory.cc
index 0fecca7c3e8001fb5b3aa4d5a41e3bbcb92aeb83..81d34b9161bd0af27e0c52143fa5bd272b3ae795 100644
--- a/content/renderer/media/webrtc/peer_connection_dependency_factory.cc
+++ b/content/renderer/media/webrtc/peer_connection_dependency_factory.cc
@@ -65,8 +65,6 @@ struct {
   const char* constraint;
   const media::AudioParameters::PlatformEffectsMask effect;
 } const kConstraintEffectMap[] = {
-  { content::kMediaStreamAudioDucking,
-    media::AudioParameters::DUCKING },
   { webrtc::MediaConstraintsInterface::kGoogEchoCancellation,
     media::AudioParameters::ECHO_CANCELLER },
 };
@@ -103,14 +101,6 @@ void HarmonizeConstraintsAndEffects(RTCMediaConstraints* constraints,
         }
         DVLOG(1) << "Disabling constraint: "
                  << kConstraintEffectMap[i].constraint;
-      } else if (kConstraintEffectMap[i].effect ==
-                 media::AudioParameters::DUCKING && value && !is_mandatory) {
-        // Special handling of the DUCKING flag that sets the optional
-        // constraint to |false| to match what the device will support.
-        constraints->AddOptional(kConstraintEffectMap[i].constraint,
-            webrtc::MediaConstraintsInterface::kValueFalse, true);
-        // No need to modify |effects| since the ducking flag is already off.
-        DCHECK((*effects & media::AudioParameters::DUCKING) == 0);
       }
     }
   }