Make DisplayItemClient an interface

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

Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
index 0de87d8988f8e085d59700ab766c223cefb2b0e4..2bf0e237ad99b48cb5459d8df8411a8235460e35 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.h
@@ -68,7 +68,7 @@ enum GraphicsLayerUpdateScope {
 //
 // Currently (Oct. 2013) there is one CompositedLayerMapping for each Layer,
 // but this is likely to evolve soon.
-class CORE_EXPORT CompositedLayerMapping final : public GraphicsLayerClient {
+class CORE_EXPORT CompositedLayerMapping final : public GraphicsLayerClient, public DisplayItemClient {

[pdr., 2015/12/05 21:39:19]

If the plan is to move invalidation bits and rects to DisplayItemClient, CLM
feels pretty weird having those. Should we be using the GraphicsLayer instead of
CLM as a client?

[Xianzhu, 2015/12/07 17:14:00]

Yes. Done.

Perhaps we can also have a CacheableDisplayItemClient for invalidation bits and
rects, so that non-cacheable display item clients don't need to care about these
methods. 

 
     WTF_MAKE_NONCOPYABLE(CompositedLayerMapping); USING_FAST_MALLOC(CompositedLayerMapping);
 public:
@@ -127,8 +127,8 @@ public:
     // If |visualRect| is not nullptr, it contains all pixels that might be painted by the display item client,
     // in coordinate space of the layer's layout object.
     // |visualRect| can be nullptr if we know it's unchanged and PaintController has cached the previous value.
-    void invalidateDisplayItemClient(const DisplayItemClientWrapper&, PaintInvalidationReason, const LayoutRect* visualRect);
-    void invalidateDisplayItemClientOnScrollingContentsLayer(const DisplayItemClientWrapper&, PaintInvalidationReason, const LayoutRect* visualRect);
+    void invalidateDisplayItemClient(const DisplayItemClient&, PaintInvalidationReason, const LayoutRect* visualRect);
+    void invalidateDisplayItemClientOnScrollingContentsLayer(const DisplayItemClient&, PaintInvalidationReason, const LayoutRect* visualRect);
 
     // Notification from the layoutObject that its content changed.
     void contentChanged(ContentChangeType);
@@ -212,8 +212,7 @@ public:
 
     void updateScrollingBlockSelection();
 
-    DisplayItemClient displayItemClient() const { return toDisplayItemClient(this); }
-    String debugName() const { return "CompositedLayerMapping for " + owningLayer().debugName(); }
+    String debugName() const override { return "CompositedLayerMapping for " + owningLayer().debugName(); }
 
 private:
     IntRect recomputeInterestRect(const GraphicsLayer*) const;