Bug 927349 part 12 - Store the initial time of animations on layers so start times can be resolved after-the-fact; r=nical

gfx/layers/ipc/LayersMessages.ipdlh

@@ -173,6 +173,11 @@ struct Animation {
   // delay.  If the delay is changed dynamically, the layer's data will
   // be updated.
   TimeStamp startTime;
+  // The value of the animation's current time at the moment it was created.
+  // For animations that are waiting to start, their startTime will be null.
+  // Once the animation is ready to start, we calculate an appropriate value
+  // of startTime such that we begin playback from initialCurrentTime.
+  TimeDuration initialCurrentTime;
   TimeDuration duration;
   // For each frame, the interpolation point is computed based on the
   // startTime, the direction, the duration, and the current time.

layout/base/nsDisplayList.cpp

@@ -67,6 +67,12 @@
 #include "nsCaret.h"
 #include "nsISelection.h"
 
+// GetCurrentTime is defined in winbase.h as zero argument macro forwarding to
+// GetTickCount().
+#ifdef GetCurrentTime
+#undef GetCurrentTime
+#endif
+
 using namespace mozilla;
 using namespace mozilla::layers;
 using namespace mozilla::dom;
@@ -358,6 +364,8 @@ AddAnimationForProperty(nsIFrame* aFrame, nsCSSProperty aProperty,
   const AnimationTiming& timing = aPlayer->GetSource()->Timing();
   animation->startTime() = aPlayer->Timeline()->ToTimeStamp(
                              aPlayer->GetStartTime().Value() + timing.mDelay);
+  animation->initialCurrentTime() = aPlayer->GetCurrentTime().Value()
+                                    - timing.mDelay;
   animation->duration() = timing.mIterationDuration;
   animation->iterationCount() = timing.mIterationCount;
   animation->direction() = timing.mDirection;