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

Source/core/animation/AnimationClock.cpp

 /*
  * 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 16 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/animation/AnimationClock.h"
 
 #include "wtf/CurrentTime.h"
 #include <math.h>
 
-namespace {
-
-// FIXME: This is an approximation of time between frames, used when
-// ticking the animation clock outside of animation frame callbacks.
-// Ideally this would be generated by the compositor.
-const double approximateFrameTime = 1 / 60.0;
-
-}
-
 namespace WebCore {
 
 unsigned AnimationClock::s_currentTask = 0;
 
-void AnimationClock::updateTime(double time)
+void AnimationClock::updateTime(blink::WebFrameTime frameTime)
 {
-    if (time > m_time)
-        m_time = time;
+    ASSERT(!frameTime.isNull());
+    ASSERT(internalCurrentTime() <= frameTime.displayFrameTime);
+    m_frameTime = frameTime;
     m_currentTask = s_currentTask;
 }
 
 double AnimationClock::currentTime()
 {
+    ASSERT(!m_frameTime.isNull());
+    ASSERT(m_frameTime.displayFrameTime >= 0);
+    ASSERT(m_frameTime.predictedNextDisplayFrameTime >= 0);
+    return internalCurrentTime();
+}
+
+double AnimationClock::internalCurrentTime()
+{
     if (m_currentTask != s_currentTask) {
-        const double currentTime = m_monotonicallyIncreasingTime();
-        if (m_time < currentTime) {
-            // Advance to the first estimated frame after the current time.
-            const double frameShift = fmod(currentTime - m_time, approximateFrameTime);
-            const double newTime = currentTime + (approximateFrameTime - frameShift);
-            ASSERT(newTime >= currentTime);
-            ASSERT(newTime <= currentTime + approximateFrameTime);
-            updateTime(newTime);
-        } else {
-            m_currentTask = s_currentTask;
-        }
+        return m_frameTime.predictedNextDisplayFrameTime;
     }
-    return m_time;
+    return m_frameTime.displayFrameTime;

[jamesr, 2014/07/08 05:00:35]

in particular this value...

+}
+
+void AnimationClock::clearTimeForTesting()
+{
+    m_frameTime = blink::WebFrameTime();
+    m_currentTask = 0;
+    s_currentTask = 0;
+}
+
+void AnimationClock::tickTimeForTesting()
+{
+    double nextTime = m_frameTime.predictedNextDisplayFrameTime;
+    if (nextTime == blink::WebFrameTime::Undefined()) {
+        nextTime = WTF::monotonicallyIncreasingTime();
+    }
+
+    // AnimationClock doesn't use lastFrameTime or renderDeadline so we just
+    // use dummy values when testing.
+    updateTime(
+        blink::WebFrameTime(
+            blink::WebFrameTime::Undefined(),
+            blink::WebFrameTime::Undefined(),
+            nextTime,
+            nextTime + (1 / 60.0)));
 }
 
 void AnimationClock::resetTimeForTesting()
 {
-    m_time = 0;
-    m_currentTask = 0;
-    s_currentTask = 0;
+    clearTimeForTesting();
+    tickTimeForTesting();
 }
-
 }