Add support for audio device selection in AppRTCDemo.

Summary:

- Creates a list of available (possible to select) audio devices.
- Automatically selects (routes audio) the "best/default" audio device.
- If possible, starts a proximity sensor that will switch between headset earpiece and speaker phone based on how close the a person's ear the mobile device is held.

TBR=glaznev

BUG=4103,4109

Review URL: https://webrtc-codereview.appspot.com/31239004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7978 4adac7df-926f-26a2-2b94-8c16560cd09d

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

@@ -203,7 +203,14 @@ public class AppRTCDemoActivity extends Activity
 
     // Create and audio manager that will take care of audio routing,
     // audio modes, audio device enumeration etc.
-    audioManager = AppRTCAudioManager.create(this);
+    audioManager = AppRTCAudioManager.create(this, new Runnable() {
+        // This method will be called each time the audio state (number and
+        // type of devices) has been changed.
+        public void run() {
+          onAudioManagerChangedState();
+        }
+      }
+    );
 
     final Intent intent = getIntent();
     Uri url = intent.getData();
@@ -294,6 +301,11 @@ public class AppRTCDemoActivity extends Activity
     }
   }
 
+  private void onAudioManagerChangedState() {
+    // TODO(henrika): disable video if AppRTCAudioManager.AudioDevice.EARPIECE
+    // is active.
+  }
+
   // Disconnect from remote resources, dispose of local resources, and exit.
   private void disconnect() {
     if (appRtcClient != null) {
@@ -595,5 +607,4 @@ public class AppRTCDemoActivity extends Activity
       disconnectWithErrorMessage(description);
     }
   }
-
 }