events: Change gesture-event handler in EventHandler to not return any values.

ash/wm/user_activity_detector_unittest.cc

Index: ash/wm/user_activity_detector_unittest.cc
diff --git a/ash/wm/user_activity_detector_unittest.cc b/ash/wm/user_activity_detector_unittest.cc
index 14c48a1a1d602e9a7e907eb32f2991682394ab9f..2aa0ef5f69453cbd46ebbd4443b53b395f906577 100644
--- a/ash/wm/user_activity_detector_unittest.cc
+++ b/ash/wm/user_activity_detector_unittest.cc
@@ -127,7 +127,8 @@ TEST_F(UserActivityDetectorTest, Basic) {
       base::TimeDelta::FromMilliseconds(base::Time::Now().ToDoubleT() * 1000),
       ui::GestureEventDetails(ui::ET_GESTURE_TAP, 0, 0), 0U);
   SetEventTarget(window.get(), &gesture_event);
-  EXPECT_FALSE(detector_->OnGestureEvent(&gesture_event));
+  detector_->OnGestureEvent(&gesture_event);
+  EXPECT_FALSE(gesture_event.handled());
   EXPECT_EQ(1, observer_->num_invocations());
   observer_->reset_stats();
 }