Convert LooperExecutorTest in AppRTC Demo into JUnit test

webrtc/examples/androidapp/src/org/appspot/apprtc/util/LooperExecutor.java

Index: webrtc/examples/androidapp/src/org/appspot/apprtc/util/LooperExecutor.java
diff --git a/webrtc/examples/androidapp/src/org/appspot/apprtc/util/LooperExecutor.java b/webrtc/examples/androidapp/src/org/appspot/apprtc/util/LooperExecutor.java
index 731630405a0d1f279ae76e32935cd8e6ce96d8d5..fe8aa0625a0cf037a9ec1d4ad5eaa7dca3bfc620 100644
--- a/webrtc/examples/androidapp/src/org/appspot/apprtc/util/LooperExecutor.java
+++ b/webrtc/examples/androidapp/src/org/appspot/apprtc/util/LooperExecutor.java
@@ -71,7 +71,7 @@ public class LooperExecutor extends Thread implements Executor {
     handler.post(new Runnable() {
       @Override
       public void run() {
-        Looper.myLooper().quit();
+        handler.getLooper().quit();

[sakal, 2016/05/18 12:18:39]

This change was required because when using Robolectric, runnables are run on
the main thread. So Looper.myLooper() would return the main looper, which cannot
be quit. This should work identically to the existing line on native Android and
also works under Robolectric.

         Log.d(TAG, "Looper thread finished.");
       }
     });
@@ -130,4 +130,10 @@ public class LooperExecutor extends Thread implements Executor {
     }
   }
 
+  /**
+   * Access to handler for testing purposes

[magjed_webrtc, 2016/05/19 12:17:12]

nit: Add dot at end of sentence.

[sakal, 2016/05/19 13:04:38]

Done.

+   */
+  Handler getHandler() {
+    return handler;
+  }
 }