Fix black background when locking with fullscreen window:

base/time.h

 // 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.
 
 // Time represents an absolute point in time, internally represented as
 // microseconds (s/1,000,000) since the Windows epoch (1601-01-01 00:00:00 UTC)
 // (See http://crbug.com/14734).  System-dependent clock interface routines are
 // defined in time_PLATFORM.cc.
 //
 // TimeDelta represents a duration of time, internally represented in
@@ skipping 620 matching lines @@
 #if defined(OS_WIN)
   typedef DWORD (*TickFunctionType)(void);
   static TickFunctionType SetMockTickFunction(TickFunctionType ticker);
 #endif
 };
 
 inline TimeTicks TimeDelta::operator+(TimeTicks t) const {
   return TimeTicks(t.ticks_ + delta_);
 }
 
+// TimeFactory ----------------------------------------------------------------
+
+class BASE_EXPORT TimeFactory {
+ public:
+  virtual Time TimeNow() = 0;
+  virtual TimeTicks TimeTicksNow() = 0;
+  virtual TimeTicks TimeTicksHighResNow() = 0;
+
+  static TimeFactory* instance() { return instance_; }
+
+ protected:
+  static TimeFactory* instance_;
+};
+
 }  // namespace base
 
 #endif  // BASE_TIME_H_