Add Mic Toggle button to AppRTCDemo (Android).

webrtc/examples/androidapp/src/org/appspot/apprtc/PeerConnectionClient.java

Index: webrtc/examples/androidapp/src/org/appspot/apprtc/PeerConnectionClient.java
diff --git a/webrtc/examples/androidapp/src/org/appspot/apprtc/PeerConnectionClient.java b/webrtc/examples/androidapp/src/org/appspot/apprtc/PeerConnectionClient.java
index 69172c33a1ac6458ecddaab1c4b0ef88ff8ad3b5..9c33b6159a8da75bebcccafc734d24fb9d30a448 100644
--- a/webrtc/examples/androidapp/src/org/appspot/apprtc/PeerConnectionClient.java
+++ b/webrtc/examples/androidapp/src/org/appspot/apprtc/PeerConnectionClient.java
@@ -17,6 +17,7 @@ import android.util.Log;
 
 import org.appspot.apprtc.AppRTCClient.SignalingParameters;
 import org.appspot.apprtc.util.LooperExecutor;
+import org.webrtc.AudioTrack;
 import org.webrtc.CameraEnumerationAndroid;
 import org.webrtc.DataChannel;
 import org.webrtc.EglBase;
@@ -124,6 +125,9 @@ public class PeerConnectionClient {
   private boolean renderVideo;
   private VideoTrack localVideoTrack;
   private VideoTrack remoteVideoTrack;
+  // enableAudio is set to true if audio should be sent.
+  private boolean enableAudio;
+  private AudioTrack localAudioTrack;
 
   /**
    * Peer connection parameters.
@@ -252,6 +256,8 @@ public class PeerConnectionClient {
     renderVideo = true;
     localVideoTrack = null;
     remoteVideoTrack = null;
+    enableAudio = true;
+    localAudioTrack = null;
     statsTimer = new Timer();
 
     executor.execute(new Runnable() {
@@ -492,9 +498,7 @@ public class PeerConnectionClient {
       mediaStream.addTrack(createVideoTrack(videoCapturer));
     }
 
-    mediaStream.addTrack(factory.createAudioTrack(
-        AUDIO_TRACK_ID,
-        factory.createAudioSource(audioConstraints)));
+    mediaStream.addTrack(createAudioTrack());
     peerConnection.addStream(mediaStream);
 
     if (peerConnectionParameters.aecDump) {
@@ -605,6 +609,18 @@ public class PeerConnectionClient {
     }
   }
 
+  public void setAudioEnabled(final boolean enable) {
+    executor.execute(new Runnable() {
+      @Override
+      public void run() {
+        enableAudio = enable;
+        if (localAudioTrack != null) {
+          localAudioTrack.setEnabled(enableAudio);
+        }
+      }
+    });
+  }
+
   public void setVideoEnabled(final boolean enable) {
     executor.execute(new Runnable() {
       @Override
@@ -749,6 +765,14 @@ public class PeerConnectionClient {
     });
   }
 
+  private AudioTrack createAudioTrack() {
+    localAudioTrack = factory.createAudioTrack(
+        AUDIO_TRACK_ID,
+        factory.createAudioSource(audioConstraints));
+    localAudioTrack.setEnabled(enableAudio);

[AlexG, 2016/03/22 16:49:20]

nit: enableAudio is always true in this call? May be replace with
localAudioTrack.setEnabled(true /* enableAudio */) ?

[the sun, 2016/03/23 08:25:44]

Hmm, well, the role of PeerConnectionClient actually isn't clear to me - it
seems to represent both a PC factory and a PC. So I decided to play it safe and
do the same for audio as is already being done for video. createVideoTrack() is
also called from createPeerConnectionInternal() so the renderVideo flag has the
same role as enableAudio. If we can always enable the tracks here, I believe
both create track functions should be updated in the same way, and we can do
that in a separate CL.

+    return localAudioTrack;
+  }
+
   private VideoTrack createVideoTrack(VideoCapturerAndroid capturer) {
     videoSource = factory.createVideoSource(capturer, videoConstraints);