Constrain transform animation direct compositing reason to transforms.

third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.h

Index: third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.h
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.h b/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.h
index 6b4ab0666e6f8f7f6de615752c506735f62bbbcf..b2afffc65a30625124853778fdfe8d35026bfbb5 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.h
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.h
@@ -5,6 +5,7 @@
 #ifndef CompositingReasonFinder_h
 #define CompositingReasonFinder_h
 
+#include "core/CoreExport.h"
 #include "core/layout/compositing/CompositingTriggers.h"
 #include "platform/graphics/CompositingReasons.h"
 #include "wtf/Allocator.h"
@@ -17,7 +18,7 @@ class LayoutObject;
 class ComputedStyle;
 class LayoutView;
 
-class CompositingReasonFinder {
+class CORE_EXPORT CompositingReasonFinder {
   DISALLOW_NEW();
   WTF_MAKE_NONCOPYABLE(CompositingReasonFinder);
 
@@ -32,6 +33,7 @@ class CompositingReasonFinder {
   bool hasOverflowScrollTrigger() const;
   bool requiresCompositingForScrollableFrame() const;
   static bool requiresCompositingForAnimation(const ComputedStyle&);
+  static bool requiresCompositingForTransformAnimation(const ComputedStyle&);
   static bool requiresCompositingForTransform(const LayoutObject&);
 
  private: