Fixing 2D canvas invalidation region tracking.

Source/core/html/canvas/CanvasRenderingContext2D.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012, 2013 Intel Corporation. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
@@ skipping 1727 matching lines @@
         *dirtyRect = canvasRect;
 
     return true;
 }
 
 void CanvasRenderingContext2D::didDraw(const FloatRect& dirtyRect)
 {
     if (dirtyRect.isEmpty())
         return;
 
-    // If we are drawing to hardware and we have a composited layer, just invalidate layer.
-    if (isAccelerated() && platformLayer()) {

[Stephen White, 2014/07/17 15:28:19]

Can we get rid of the platformLayer() override now? It looks like this might be
the only use.

[Justin Novosad, 2014/07/17 17:07:21]

We can't. That method is a virtual override from CanvasRenderingContext and is
invoked by CompositedLayerMapping.

-        platformLayer()->invalidateRect(dirtyRect);
-        canvas()->clearCopiedImage();
-        canvas()->notifyObserversCanvasChanged(dirtyRect);
-        return;
-    }
-
     canvas()->didDraw(dirtyRect);
 }
 
 GraphicsContext* CanvasRenderingContext2D::drawingContext() const
 {
     if (isContextLost())
         return 0;
     return canvas()->drawingContext();
 }
 
@@ skipping 680 matching lines @@
 
 unsigned CanvasRenderingContext2D::hitRegionsCount() const
 {
     if (m_hitRegionManager)
         return m_hitRegionManager->getHitRegionsCount();
 
     return 0;
 }
 
 } // namespace WebCore