Change ui::Event::time_stamp from TimeDelta to TimeTicks

ash/keyboard_uma_event_filter.cc

 // Copyright 2013 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 "ash/keyboard_uma_event_filter.h"
 
 #include "base/metrics/histogram.h"
 #include "ui/events/event.h"
 
 namespace {
@@ skipping 12 matching lines @@
 KeyboardUMAEventFilter::~KeyboardUMAEventFilter() {}
 
 void KeyboardUMAEventFilter::OnKeyEvent(ui::KeyEvent* event) {
   // This is a rough approximation, so assume that each key release is the
   // result of a typed key.
   if (event->type() != ui::ET_KEY_RELEASED)
     return;
 
   // Reset the timer on non-character keystrokes.
   if (!isprint(event->GetCharacter())) {
-    last_keystroke_time_ = base::TimeDelta();
+    last_keystroke_time_ = base::TimeTicks();
     return;
   }
 
   if (last_keystroke_time_.ToInternalValue() == 0) {
     last_keystroke_time_ = event->time_stamp();
     return;
   }
 
   base::TimeDelta delta = event->time_stamp() - last_keystroke_time_;
   if (delta < base::TimeDelta::FromSeconds(kKeystrokeThresholdInSeconds))
     UMA_HISTOGRAM_TIMES("Keyboard.KeystrokeDeltas", delta);
 
   last_keystroke_time_ = event->time_stamp();
 }
 
 }  // namespace ash