Defer starting of animations until after compositing update

Source/core/animation/DocumentAnimations.h

Index: Source/core/animation/DocumentAnimations.h
diff --git a/Source/core/animation/DocumentAnimations.h b/Source/core/animation/DocumentAnimations.h
index b952c532ec16b927ce4eb7b7a61a17b57eb18134..9772eef3c1a4edbef8061b2a0d7188bf5cd40404 100644
--- a/Source/core/animation/DocumentAnimations.h
+++ b/Source/core/animation/DocumentAnimations.h
@@ -41,12 +41,28 @@ class Node;
 
 class DocumentAnimations  {
 public:
-    static void serviceOnAnimationFrame(Document&, double monotonicAnimationStartTime);
+    static void serviceOnFrameStart(Document&, double monotonicAnimationStartTime);

[abarth-chromium, 2014/02/20 17:52:00]

Can we rename this function to indicate what it does?  It's not possible to tell
from the name what this function does.

[dstockwell, 2014/02/24 06:03:25]

Done. I split and renamed the functions of DocumentAnimations.

     static void serviceBeforeGetComputedStyle(Node&, CSSPropertyID);
-    static void serviceAfterStyleRecalc(Document&);
+
+    class ServiceOnFrameEndScope {

[abarth-chromium, 2014/02/20 17:52:00]

This is a wacky pattern for calling a function.  Why not just call the function?

[dstockwell, 2014/02/20 18:22:01]

Isn't this the same pattern as DocumentLifecycle::Scope ?

RenderLayerCompositor::updateCompositingLayers has multiple points of return,
this needs to be called at the end.

+        WTF_MAKE_NONCOPYABLE(ServiceOnFrameEndScope);
+    public:
+        ServiceOnFrameEndScope(Document& document)
+            : m_document(document)
+        {
+        }
+        ~ServiceOnFrameEndScope()
+        {
+            DocumentAnimations::serviceOnFrameEnd(m_document);
+        }
+
+    private:
+        Document& m_document;
+    };
 
 private:
     DocumentAnimations() { }
+    static void serviceOnFrameEnd(Document&);
 };
 
 } // namespace