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

public/platform/WebContentLayerClient.h

 /*
  * Copyright (C) 2011 Google 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
@@ skipping 24 matching lines @@
 struct WebRect;
 
 class BLINK_PLATFORM_EXPORT WebContentLayerClient {
 public:
     enum GraphicsContextStatus { GraphicsContextEnabled, GraphicsContextDisabled };
 
     // 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.

[Stephen Chennney, 2015/02/03 17:15:23]

This comment is referring to something that no longer exists. Some time ago I
removed the code but not the comment. 

     // 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;
+    // Temporary to enable Blink+Chromium commit.
+    virtual void paintContents(WebDisplayItemList* list, const WebRect& clip, GraphicsContextStatus status = GraphicsContextEnabled)
+    {
+        paintContents(list, clip, false, status);
+    }
+
+    // Paints the content area for the layer, typically dirty rects submitted
+    // through WebContentLayer::setNeedsDisplay, 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 |clearCaches| flag specifies whether the WebItemDisplayList should regenerate all
+    // content (when |clearCaches| is true) or is free to use cached content. It is only set true
+    // for performance testing.
+    // The |disableContext| enum controls most processing in GraphicsContext to isolate the painting
+    // code in performance tests. Current code always sets it to GraphicsContextEnabled.
+    virtual void paintContents(
+        WebDisplayItemList*,
+        const WebRect& clip,
+        const bool clearCaches = false,

[chrishtr, 2015/02/03 20:01:21]

How about an enum { ShouldRespectPaintCache, ShouldIgnorePaintCache} instead of
the bool argument?

+        GraphicsContextStatus = GraphicsContextEnabled) = 0;
 
 protected:
     virtual ~WebContentLayerClient() { }
 };
 
 } // namespace blink
 
 #endif // WebContentLayerClient_h