Move logic of recording main thread scrolling reasons from cc to blink::ScrollManager

third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h

Index: third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
index 2f4cfde9a0dcddc4e99acaa5988d78a598416547..315654a21b45289489f8925ad60900ad9b97ea91 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
+++ b/third_party/WebKit/Source/core/paint/PaintLayerScrollableArea.h
@@ -479,14 +479,12 @@ class CORE_EXPORT PaintLayerScrollableArea final
   StickyConstraintsMap& GetStickyConstraintsMap() {
     return EnsureRareData().sticky_constraints_map_;
   }
+
   void InvalidateAllStickyConstraints();
   void InvalidateStickyConstraintsFor(PaintLayer*,
                                       bool needs_compositing_update = true);
-
-  void RemoveStyleRelatedMainThreadScrollingReasons();
-  void AddStyleRelatedMainThreadScrollingReasons(const uint32_t);
-  bool HasMainThreadScrollingReason(uint32_t reason) const {
-    return reasons_ & reason;
+  uint32_t GetNonCompositedMainThreadScrollingReasons() {
+    return non_composited_main_thread_scrolling_reasons_;
   }
 
   uint64_t Id() const;
@@ -597,7 +595,7 @@ class CORE_EXPORT PaintLayerScrollableArea final
   std::unique_ptr<PaintLayerScrollableAreaRareData> rare_data_;
 
   // MainThreadScrollingReason due to the properties of the LayoutObject
-  uint32_t reasons_;
+  uint32_t non_composited_main_thread_scrolling_reasons_;

[tdresser, 2017/04/11 18:50:47]

Is "non composited" redundant with "main thread"?

[yigu, 2017/04/11 21:28:11]

This is to differentiate the reasons that caused main thread scrolling for an
element but we also "composite" that element. e.g. element with fixed background
attachment and "will-change:transform;".

 
 #if DCHECK_IS_ON()
   bool has_been_disposed_;