Remove unused message_loop_ field in GestureProviderTest

ui/events/gesture_detection/gesture_provider_unittest.cc

Index: ui/events/gesture_detection/gesture_provider_unittest.cc
diff --git a/ui/events/gesture_detection/gesture_provider_unittest.cc b/ui/events/gesture_detection/gesture_provider_unittest.cc
index 3cc45f938d5bff6dd143677431979a64996c276f..064e4f76e8cc2f0c37f98f94120daf9d3ac19a63 100644
--- a/ui/events/gesture_detection/gesture_provider_unittest.cc
+++ b/ui/events/gesture_detection/gesture_provider_unittest.cc
@@ -416,7 +416,6 @@ class GestureProviderTest : public testing::Test, public GestureProviderClient {
   std::vector<GestureEventData> gestures_;
   scoped_ptr<GestureProvider> gesture_provider_;
   scoped_ptr<GestureEventData> active_scroll_begin_event_;
-  base::MessageLoopForUI message_loop_;
 };
 
 // Verify that a DOWN followed shortly by an UP will trigger a single tap.