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
 // microseconds.
 //
 // TimeTicks represents an abstract time that is most of the time incrementing
 // for use in measuring time durations. It is internally represented in
 // microseconds.  It can not be converted to a human-readable time, but is
 // guaranteed not to decrease (if the user changes the computer clock,
 // Time::Now() may actually decrease or jump).  But note that TimeTicks may
 // "stand still", for example if the computer suspended.
 //
+// TimeFactory can be used to override values returned by Time::Now and
+// TimeTicks::Now for test purposes.
+//
 // These classes are represented as only a 64-bit value, so they can be
 // efficiently passed by value.
 
 #ifndef BASE_TIME_H_
 #define BASE_TIME_H_
 
 #include <time.h>
 
 #include "base/atomicops.h"
 #include "base/base_export.h"
@@ skipping 601 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 ----------------------------------------------------------------
+
+// This class should be subclassed to provide test values for Time::Now and
+// TimeTicks::Now. Subclass instance should register itself by setting
+// |instance_| fields.
+class BASE_EXPORT TimeFactory {
+ public:
+  // Substitutes value for Time::Now().
+  virtual Time TimeNow() = 0;
+  // Substitutes value for TimeTicks::Now()
+  virtual TimeTicks TimeTicksNow() = 0;
+
+  // Returns instance of |TimeFactory|. If null, system time routines are used.
+  static TimeFactory* instance() { return instance_; }
+ protected:
+  // Implementation of TimeFactory (set by implementing subclasses).
+  static TimeFactory* instance_;
+};
+
 }  // namespace base
 
 #endif  // BASE_TIME_H_