Make the web-animations engine use the passed in blink::WebFrameTime values.

public/platform/WebFrameTime.h

 /*
  * Copyright (C) 2014 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 18 matching lines @@
  */
 
 #ifndef WebFrameTime_h
 #define WebFrameTime_h
 
 #include "WebCommon.h"
 
 namespace blink {
 
 struct WebFrameTime {
+    const static int64_t Undefined = -1;
+
+    WebFrameTime()
+        : lastFrameTime(Undefined)
+        , renderDeadline(Undefined)
+        , displayFrameTime(Undefined)
+        , predictedNextDisplayFrameTime(Undefined)
+    { }
+
     WebFrameTime(double lastFrameTime, double renderDeadline, double displayFrameTime, double predictedNextDisplayFrameTime)
         : lastFrameTime(lastFrameTime)
         , renderDeadline(renderDeadline)
         , displayFrameTime(displayFrameTime)
         , predictedNextDisplayFrameTime(predictedNextDisplayFrameTime)
     { }
 
+    bool isNull() const
+    {
+        return (
+            lastFrameTime == Undefined
+            && renderDeadline == Undefined
+            && displayFrameTime == Undefined
+            && predictedNextDisplayFrameTime == Undefined);
+    }
+
     // FIXME(mithro): Upgrade the time in CLOCK_MONOTONIC values to use a
     // TimeTick like class rather than a bare double.
 
     // Time in CLOCK_MONOTONIC that is the most recent vsync time.
     double lastFrameTime;
 
     // Time in CLOCK_MONOTONIC by which rendering must be finished by to not
     // stall the pipeline.
     double renderDeadline;
 
     // Time in CLOCK_MONOTONIC that the frame will hit the glass of the display
     // if rendered within the deadline. This time may be identical to
     // lastFrameTime.
     double displayFrameTime;
 
     // Time in CLOCK_MONOTONIC that is the predicated next value for
     // displayFrameTime. The next displayFrameTime should be this value or
     // greater.
     double predictedNextDisplayFrameTime;
 };
 
 } // namespace blink
 
 #endif