Slimming Paint phase 2 compositing algorithm plumbing & skeleton display list API.

public/platform/WebContentLayerClient.h

Index: public/platform/WebContentLayerClient.h
diff --git a/public/platform/WebContentLayerClient.h b/public/platform/WebContentLayerClient.h
index abf25d77dcd1a817a4d3350c7d954628594be8cb..d81421e29a15efacf226a30a3d3772680968658f 100644
--- a/public/platform/WebContentLayerClient.h
+++ b/public/platform/WebContentLayerClient.h
@@ -32,6 +32,8 @@
 namespace blink {
 
 class WebDisplayItemList;
+class WebDisplayItemTransformTree;
+class WebDisplayList;
 struct WebRect;
 
 class BLINK_PLATFORM_EXPORT WebContentLayerClient {
@@ -69,6 +71,11 @@ public:
     // result includes data cached internally during painting.
     virtual size_t approximateUnsharedMemoryUsage() const { return 0; }
 
+    virtual const WebDisplayList* displayList() const { return 0; };

[jbroman, 2015/07/22 21:20:07]

What will cc do with the display list for a layer? In particular, will it do
anything other than paint its contents?

[chrishtr, 2015/07/22 22:09:58]

cc will raster it yeah. This is the representation of the slices of the display
list that should be rastered into this particular content layer. This way there
are no extra copies in order to get them into an iterable data structure..

+
+    // This is only set on a root graphics layer. Alternatively, this could be set on the layer tree host.
+    virtual const WebDisplayItemTransformTree* transformTree() const { return 0; };
+
 protected:
     virtual ~WebContentLayerClient() { }
 };