Blink Platform: Remove time functions from Platform.

third_party/WebKit/Source/wtf/CurrentTime.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2008 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 37 matching lines @@
 }
 
 // Provides a monotonically increasing time in seconds since an arbitrary point in the past.
 // On unsupported platforms, this function only guarantees the result will be non-decreasing.
 WTF_EXPORT double monotonicallyIncreasingTime();
 
 // Provides a timestamp that aligns with system tracing utilities on the host operating
 // system.
 WTF_EXPORT double systemTraceTime();
 
-typedef double(*TimeFunction)(void);
-void setCurrentTimeFunction(TimeFunction);
-WTF_EXPORT void setMonotonicallyIncreasingTimeFunction(TimeFunction);
-void setSystemTraceTimeFunction(TimeFunction);
+using TimeFunction = double (*)();
 
+// Make all the time functions (currentTime(), monotonicallyIncreasingTime(), systemTraceTime()) return the result
+// of the supplied function. Returns the pointer to the old time function. For both setting and getting, nullptr means
+// using the default timing function returning the actual time.
+WTF_EXPORT TimeFunction setTimeFunctionsForTesting(TimeFunction);
 
 } // namespace WTF
 
 using WTF::currentTime;
 using WTF::currentTimeMS;
 using WTF::monotonicallyIncreasingTime;
 using WTF::systemTraceTime;
+using WTF::TimeFunction;
+using WTF::setTimeFunctionsForTesting;
 
 #endif // CurrentTime_h