WebGL: Free temporary GPU resources held by inactive or hidden WebGL.

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 2275 matching lines @@
     case MiddleTextBaseline:
         return -fontMetrics.descent() + fontMetrics.height() / 2;
     case AlphabeticTextBaseline:
     default:
         // Do nothing.
         break;
     }
     return 0;
 }
 
+void CanvasRenderingContext2D::setIsHidden(bool hidden)
+{
+    ImageBuffer* buffer = canvas()->buffer();
+    if (buffer)
+        buffer->setIsHidden(hidden);
+}
+
 blink::WebLayer* CanvasRenderingContext2D::platformLayer() const
 {
     return canvas()->buffer() ? canvas()->buffer()->platformLayer() : 0;
 }
 
 bool CanvasRenderingContext2D::imageSmoothingEnabled() const
 {
     return state().m_imageSmoothingEnabled;
 }
 
@@ skipping 120 matching lines @@
     c->setAlphaAsFloat(1.0);
     c->clearShadow();
     c->setCompositeOperation(CompositeSourceOver, blink::WebBlendModeNormal);
     c->drawFocusRing(path, focusRingWidth, focusRingOutline, focusRingColor);
     c->restore();
 
     didDraw(dirtyRect);
 }
 
 } // namespace WebCore