Refactor stopCapture to be asynchronous in VideoCapturerAndroid.

webrtc/api/android/java/src/org/webrtc/Camera2Capturer.java

Index: webrtc/api/android/java/src/org/webrtc/Camera2Capturer.java
diff --git a/webrtc/api/android/java/src/org/webrtc/Camera2Capturer.java b/webrtc/api/android/java/src/org/webrtc/Camera2Capturer.java
index c3c912acd5bbdc922a0308850d31582f72ae2737..644c70b2f725c8fbdddfb7ff234750b39dea20ba 100644
--- a/webrtc/api/android/java/src/org/webrtc/Camera2Capturer.java
+++ b/webrtc/api/android/java/src/org/webrtc/Camera2Capturer.java
@@ -777,6 +777,8 @@ public class Camera2Capturer implements
 
   @Override
   public void dispose() {
+    stopCapture();
+
     synchronized (cameraStateLock) {
       waitForCameraToStopIfStopping();
 
@@ -798,7 +800,7 @@ public class Camera2Capturer implements
       waitForCameraToStartIfStarting();
 
       if (cameraState != CameraState.RUNNING) {
-        Logging.w(TAG, "stopCapture called for already stopped camera.");
+        Logging.d(TAG, "stopCapture called for already stopped camera.");
         return;
       }