Blink side of changes to enable cache clearing without a flag.

public/platform/WebContentLayerClient.h

Index: public/platform/WebContentLayerClient.h
diff --git a/public/platform/WebContentLayerClient.h b/public/platform/WebContentLayerClient.h
index 552fe576d02d427ff52d36b4a88fec6b5c680e79..2836b2541f5fb682ea1d94f7dc6c9c3e9332fa11 100644
--- a/public/platform/WebContentLayerClient.h
+++ b/public/platform/WebContentLayerClient.h
@@ -37,19 +37,44 @@ struct WebRect;
 class BLINK_PLATFORM_EXPORT WebContentLayerClient {
 public:
     enum GraphicsContextStatus { GraphicsContextEnabled, GraphicsContextDisabled };
+    enum PaintingControlSetting { PaintDefaultBehavior, DisplayListConstructionDisabled, DisplayListCachingDisabled };
+
+    // Temporary until we rename the GraphicsContextStatus on the chromium side.
+    void paintContents(WebCanvas* canvas, const WebRect& clip, GraphicsContextStatus status = GraphicsContextEnabled)
+    {
+        paintContents(canvas, clip,
+            status == GraphicsContextEnabled ? PaintDefaultBehavior : DisplayListConstructionDisabled);
+    }
+
+    // Temporary until we rename the GraphicsContextStatus on the chromium side.
+    void paintContents(
+        WebDisplayItemList* itemList,
+        const WebRect& clip,
+        GraphicsContextStatus status = GraphicsContextEnabled)
+    {
+        paintContents(itemList, clip,
+            status == GraphicsContextEnabled ? PaintDefaultBehavior : DisplayListConstructionDisabled);
+    }
 
     // Paints the content area for the layer, typically dirty rects submitted
     // through WebContentLayer::setNeedsDisplay, submitting drawing commands
     // through the WebCanvas.
     // The canvas is already clipped to the |clip| rect.
-    // Optionally, the implementation may set |opaque| to a rect covering pixels that
-    // the implementation knows are opaque. This information can be used for various
-    // optimizations.
-    // The |disableContext| enum controls most processing in
-    // GraphicsContext to isolate the painting code in performance tests.
-    virtual void paintContents(WebCanvas*, const WebRect& clip, GraphicsContextStatus = GraphicsContextEnabled) = 0;
-
-    virtual void paintContents(WebDisplayItemList*, const WebRect& clip, GraphicsContextStatus = GraphicsContextEnabled) = 0;
+    // The |PaintingControlSetting| enum controls painting to isolate different components in performance tests.
+    virtual void paintContents(WebCanvas*, const WebRect& clip, PaintingControlSetting = PaintDefaultBehavior) = 0;
+
+    // Paints the content area for the layer, typically dirty rects submitted
+    // through WebContentLayer::setNeedsDisplayInRect, submitting drawing commands
+    // to populate the WebDisplayItemList.
+    // The |clip| rect defines the region of interest. The resulting WebDisplayItemList should contain
+    // sufficient content to correctly paint the rect, but may also contain other content. The result
+    // will be clipped on playback.
+    // The |PaintingControlSetting| enum controls painting to isolate different components in performance tests.
+    // Currently the DisplayListConstructionDisabled does nothing.
+    virtual void paintContents(
+        WebDisplayItemList*,
+        const WebRect& clip,
+        PaintingControlSetting = PaintDefaultBehavior) = 0;
 
 protected:
     virtual ~WebContentLayerClient() { }