blink: Make WebMainThreadScrollingReason wrap the cc enum.

third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.h

Index: third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.h
diff --git a/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.h b/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.h
index fd48d40ca406d2b87d091cea458b4ceb8004c3fb..be99b70698838a815062f4185df6abeeb82f970a 100644
--- a/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.h
+++ b/third_party/WebKit/Source/core/page/scrolling/ScrollingCoordinator.h
@@ -30,8 +30,8 @@
 #include "core/layout/LayoutObject.h"
 #include "platform/PlatformWheelEvent.h"
 #include "platform/geometry/IntRect.h"
+#include "platform/scroll/MainThreadScrollingReason.h"
 #include "platform/scroll/ScrollTypes.h"
-#include "public/platform/WebMainThreadScrollingReason.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/text/WTFString.h"
 
@@ -140,7 +140,7 @@ protected:
 private:
     bool shouldUpdateAfterCompositingChange() const { return m_scrollGestureRegionIsDirty || m_touchEventTargetRectsAreDirty || m_shouldScrollOnMainThreadDirty || frameViewIsDirty(); }
 
-    void setShouldUpdateScrollLayerPositionOnMainThread(MainThreadScrollingReasons);
+    void setShouldUpdateScrollLayerPositionOnMainThread(uint32_t mainThreadScrollingReasons);
 
     bool hasVisibleSlowRepaintViewportConstrainedObjects(FrameView*) const;
 
@@ -162,7 +162,8 @@ private:
     HashSet<const PaintLayer*> m_layersWithTouchRects;
     bool m_wasFrameScrollable;
 
-    MainThreadScrollingReasons m_lastMainThreadScrollingReasons;
+    // A set of flags from MainThreadScrollingReason.
+    uint32_t m_lastMainThreadScrollingReasons;
 };
 
 } // namespace blink