Changing animate to beginFrame and use struct rather than naked double to allow extension.

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 10 matching lines @@
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef WebWaitableEvent_h
-#define WebWaitableEvent_h
+#ifndef WebFrameTime_h
+#define WebFrameTime_h
 
 #include "WebCommon.h"
 
 namespace blink {
 
-// Provides a thread synchronization that can be used to allow one thread to
-// wait until another thread to finish some work.
-class WebWaitableEvent {
-public:
-    virtual ~WebWaitableEvent() { }
+struct WebFrameTime {
+    WebFrameTime(double lastFrameTime, double renderDeadline, double displayFrameTime, double predictedNextDisplayFrameTime)
+        : lastFrameTime(lastFrameTime)
+        , renderDeadline(renderDeadline)
+        , displayFrameTime(displayFrameTime)
+        , predictedNextDisplayFrameTime(predictedNextDisplayFrameTime)
+    { }
 
-    // Waits indefinitely for the event to be signaled.
-    virtual void wait() = 0;
+    // FIXME(mithro): Upgrade the time in CLOCK_MONOTONIC values to use a
+    // TimeTick like class rather than a bare double.
 
-    // Puts the event in the signaled state. Causing any thread blocked on Wait
-    // to be woken up. The event state is reset to non-signaled after
-    // a waiting thread has been released.
-    virtual void signal() = 0;
+    // 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 // WebWaitableEvent_h
+#endif