Remove the MessageLoop::DestructionObserver from mojo bindings.

services/video_capture/test/mock_device_test.h

Index: services/video_capture/test/mock_device_test.h
diff --git a/services/video_capture/test/mock_device_test.h b/services/video_capture/test/mock_device_test.h
index 41e16930bd202d9579c3eb6a6e863aa2fe6481ef..4713861c88ae265a55f6caae4a9a90c4bd87c003 100644
--- a/services/video_capture/test/mock_device_test.h
+++ b/services/video_capture/test/mock_device_test.h
@@ -14,6 +14,10 @@
 #include "services/video_capture/test/mock_receiver.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+namespace base {
+class MessageLoop;
+}
+
 namespace video_capture {
 
 class MockDevice : public media::VideoCaptureDevice {