End-to-end prototype of compositor scrolling with slimming paint v2

third_party/WebKit/Source/platform/scroll/ScrollableArea.h

 /*
  * Copyright (C) 2008, 2011 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 17 matching lines @@
 
 #include "platform/PlatformExport.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/geometry/FloatQuad.h"
 #include "platform/geometry/LayoutRect.h"
 #include "platform/graphics/Color.h"
 #include "platform/heap/Handle.h"
 #include "platform/scroll/ScrollAnimatorBase.h"
 #include "platform/scroll/ScrollTypes.h"
 #include "platform/scroll/Scrollbar.h"
+#include "public/platform/WebLayerScrollClient.h"
 #include "wtf/MathExtras.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class CompositorAnimationHost;
 class CompositorAnimationTimeline;
 class GraphicsLayer;
 class HostWindow;
 class LayoutBox;
 class LayoutObject;
 class PaintLayer;
 class ProgrammaticScrollAnimator;
 struct ScrollAlignment;
 class ScrollAnchor;
 class ScrollAnimatorBase;
 class CompositorAnimationTimeline;
 
 enum IncludeScrollbarsInRect {
   ExcludeScrollbars,
   IncludeScrollbars,
 };
 
-class PLATFORM_EXPORT ScrollableArea : public GarbageCollectedMixin {
+class PLATFORM_EXPORT ScrollableArea : public GarbageCollectedMixin,
+                                       public WebLayerScrollClient {
   WTF_MAKE_NONCOPYABLE(ScrollableArea);
 
  public:
   static int pixelsPerLineStep(HostWindow*);
   static float minFractionToStepWhenPaging();
   static int maxOverlapBetweenPages();
 
   // Convert a non-finite scroll value (Infinity, -Infinity, NaN) to 0 as
   // per http://dev.w3.org/csswg/cssom-view/#normalize-non_finite-values.
   static float normalizeNonFiniteScroll(float value) {
@@ skipping 292 matching lines @@
   virtual void clearScrollableArea();
 
   virtual ScrollAnchor* scrollAnchor() { return nullptr; }
 
   virtual void didScrollWithScrollbar(ScrollbarPart, ScrollbarOrientation) {}
 
   // Returns the task runner to be used for scrollable area timers.
   // Ideally a frame-specific throttled one can be used.
   virtual RefPtr<WebTaskRunner> getTimerTaskRunner() const = 0;
 
+  // Callback for compositor-side scrolling.
+  void didScroll(const gfx::ScrollOffset&) override;
+
  protected:
   ScrollableArea();
 
   ScrollbarOrientation scrollbarOrientationFromDirection(
       ScrollDirectionPhysical) const;
   float scrollStep(ScrollGranularity, ScrollbarOrientation) const;
 
   void setScrollOrigin(const IntPoint&);
   void resetScrollOriginChanged() { m_scrollOriginChanged = false; }
 
@@ skipping 63 matching lines @@
   // vertical-lr / ltr            NO                      NO
   // vertical-lr / rtl            NO                      YES
   // vertical-rl / ltr            YES                     NO
   // vertical-rl / rtl            YES                     YES
   IntPoint m_scrollOrigin;
 };
 
 }  // namespace blink
 
 #endif  // ScrollableArea_h