Free temporary GPU and memory resources held by inactive or hidden 2D canvases

Source/platform/graphics/Canvas2DLayerManager.h

Index: Source/platform/graphics/Canvas2DLayerManager.h
diff --git a/Source/platform/graphics/Canvas2DLayerManager.h b/Source/platform/graphics/Canvas2DLayerManager.h
index e2c4e042e6585647ae81c5fed3f74b7b932e2d64..70781e33cefb969eaf627fdbd10bc39f41a676bc 100644
--- a/Source/platform/graphics/Canvas2DLayerManager.h
+++ b/Source/platform/graphics/Canvas2DLayerManager.h
@@ -35,18 +35,22 @@ namespace WebCore {
 class PLATFORM_EXPORT Canvas2DLayerManager : public blink::WebThread::TaskObserver {
 public:
     static Canvas2DLayerManager& get();
+
     void init(size_t maxBytesAllocated, size_t targetBytesAllocated);
     virtual ~Canvas2DLayerManager();
 
     void layerAllocatedStorageChanged(Canvas2DLayerBridge*, intptr_t deltaBytes);
     void layerDidDraw(Canvas2DLayerBridge*);
+    void setLayerHasFreeableResources(Canvas2DLayerBridge*);
     void layerToBeDestroyed(Canvas2DLayerBridge*);
+    void didHidePage();

[eseidel, 2013/12/19 02:56:32]

The page concept is largely leaving blink as in the out of process iframe world
blink may only know about some of teh Frames in a single page.  It's possible
didHidePage is still the right name for this however.

+
 private:
     Canvas2DLayerManager();
 
     // internal methods
     void freeMemoryIfNecessary();
-    bool isInList(Canvas2DLayerBridge*);
+    bool isInList(Canvas2DLayerBridge*) const;
     void addLayerToList(Canvas2DLayerBridge*);
     void removeLayerFromList(Canvas2DLayerBridge*);
     virtual void willProcessTask() OVERRIDE;