Track input latency with UMA stats

ui/aura/gestures/gesture_recognizer_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/memory/scoped_vector.h"
 #include "base/run_loop.h"
 #include "base/string_number_conversions.h"
 #include "base/timer.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/aura/env.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/test/aura_test_base.h"
 #include "ui/aura/test/event_generator.h"
 #include "ui/aura/test/test_window_delegate.h"
 #include "ui/aura/test/test_windows.h"
 #include "ui/base/events/event.h"
+#include "ui/base/events/event_utils.h"
 #include "ui/base/gestures/gesture_configuration.h"
 #include "ui/base/gestures/gesture_recognizer_impl.h"
 #include "ui/base/gestures/gesture_sequence.h"
 #include "ui/base/gestures/gesture_types.h"
 #include "ui/base/hit_test.h"
 #include "ui/gfx/point.h"
 #include "ui/gfx/rect.h"
 
 #include <queue>
 
@@ skipping 443 matching lines @@
   virtual ui::GestureSequence* CreateSequence(
       ui::GestureEventHelper* helper) OVERRIDE {
     return new TimerTestGestureSequence(helper);
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TimerTestGestureRecognizer);
 };
 
 base::TimeDelta GetTime() {
-  return base::Time::NowFromSystemTime() - base::Time();
+  return ui::EventTimeForNow();
 }
 
 class TimedEvents {
  private:
   int simulated_now_;
 
  public:
   TimedEvents() : simulated_now_(0) {
   }
 
@@ skipping 2555 matching lines @@
                        tes.LeapForward(40));
   root_window()->AsRootWindowHostDelegate()->OnHostTouchEvent(&move4);
   EXPECT_TRUE(delegate->scroll_update());
   EXPECT_EQ(-1, delegate->scroll_y());
 
   delegate->Reset();
 }
 
 }  // namespace test
 }  // namespace aura