PeerConnection(java): use MediaCodec for HW-accelerated video encode where available.

Still disabled by default until https://code.google.com/p/webrtc/issues/detail?id=2899 is resolved.

Also (because I needed them during development):
- make AppRTCDemo "debuggable" for extra JNI checks
- honor audio constraints served by apprtc.appspot.com
- don't "restart" video when it hasn't been stopped (affects running with the
  screen off)

BUG=2575
R=noahric@google.com

Review URL: https://webrtc-codereview.appspot.com/8269004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5539 4adac7df-926f-26a2-2b94-8c16560cd09d

talk/examples/android/src/org/appspot/apprtc/AppRTCDemoActivity.java

@@ -75,6 +75,7 @@ public class AppRTCDemoActivity extends Activity
   private static final String TAG = "AppRTCDemoActivity";
   private PeerConnectionFactory factory;
   private VideoSource videoSource;
+  private boolean videoSourceStopped;
   private PeerConnection pc;
   private final PCObserver pcObserver = new PCObserver();
   private final SDPObserver sdpObserver = new SDPObserver();
@@ -159,6 +160,7 @@ public class AppRTCDemoActivity extends Activity
     vsv.onPause();
     if (videoSource != null) {
       videoSource.stop();
+      videoSourceStopped = true;
     }
   }
 
@@ -166,7 +168,7 @@ public class AppRTCDemoActivity extends Activity
   public void onResume() {
     super.onResume();
     vsv.onResume();
-    if (videoSource != null) {
+    if (videoSource != null && videoSourceStopped) {
       videoSource.restart();
     }
   }
@@ -239,7 +241,9 @@ public class AppRTCDemoActivity extends Activity
             vsv, VideoStreamsView.Endpoint.LOCAL)));
         lMS.addTrack(videoTrack);
       }
-      lMS.addTrack(factory.createAudioTrack("ARDAMSa0"));
+      if (appRtcClient.audioConstraints() != null) {
+        lMS.addTrack(factory.createAudioTrack("ARDAMSa0"));
+      }
       pc.addStream(lMS, new MediaConstraints());
     }
     logAndToast("Waiting for ICE candidates...");