scheduler: Tell the scheduler about frame timing

public/web/WebBeginFrameArgs.h

 // Copyright 2014 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.
 
 #ifndef WebBeginFrameArgs_h
 #define WebBeginFrameArgs_h
 
 namespace blink {
 
 struct WebBeginFrameArgs {
+    WebBeginFrameArgs(double lastFrameTimeMonotonic, double deadline, double interval)
+        : lastFrameTimeMonotonic(lastFrameTimeMonotonic)
+        , deadline(deadline)
+        , interval(interval)
+    { }
+
+    // TODO: Remove this constructor once Chromium has been updated.
     WebBeginFrameArgs(double lastFrameTimeMonotonic)
         : lastFrameTimeMonotonic(lastFrameTimeMonotonic)
+        , deadline(0)
+        , interval(0)
     { }
 
     // FIXME: Upgrade the time in CLOCK_MONOTONIC values to use a TimeTick like
     // class rather than a bare double.
 
     // FIXME: Extend this class to include the fields from Chrome
     // BeginFrameArgs structure.
 
     // Time in CLOCK_MONOTONIC that is the most recent vsync time.
     double lastFrameTimeMonotonic;
+
+    // Time in CLOCK_MONOTONIC by which the renderer should finish producing the current frame. 0 means a deadline wasn't set.
+    double deadline;
+
+    // Expected delta between two successive frame times. 0 if a regular interval isn't available.
+    double interval;
 };
 
 } // namespace blink
 
 #endif