Change base::TickClock to a ref counted class.

ui/display/chromeos/x11/native_display_event_dispatcher_x11.cc

 // Copyright 2014 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/time/default_tick_clock.h"
 #include "ui/display/chromeos/x11/native_display_event_dispatcher_x11.h"
 #include "ui/display/chromeos/x11/display_mode_x11.h"
 #include "ui/display/chromeos/x11/display_snapshot_x11.h"
 #include "ui/events/platform/platform_event_source.h"
 
@@ skipping 81 matching lines @@
       return ui::POST_DISPATCH_PERFORM_DEFAULT;
     }
   }
 
   delegate_->NotifyDisplayObservers();
 
   return ui::POST_DISPATCH_PERFORM_DEFAULT;
 }
 
 void NativeDisplayEventDispatcherX11::SetTickClockForTest(
-    scoped_ptr<base::TickClock> tick_clock) {
-  tick_clock_ = tick_clock.Pass();
+    scoped_refptr<base::TickClock> tick_clock) {
+  tick_clock_.swap(tick_clock);

[Daniel Erat, 2014/10/21 16:30:10]

why swap() instead of just assigning it?

[rkc, 2014/10/21 16:54:42]

I was trying to follow this pattern that is being used a lot of places where
tick clocks were being passed in. Looking at the code, there doesn't seem to be
any performance benefit, and ideally refptr should be passed in as const-ref -
which would not allow .swap anyway.

Changed it here, and, well 30 other places :)

   startup_time_ = tick_clock_->NowTicks();
 }
 
 }  // namespace ui