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

Source/platform/graphics/Canvas2DLayerBridge.h

 /*
  * Copyright (C) 2012 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 34 matching lines @@
 }
 
 class Canvas2DLayerBridgeTest;
 
 namespace WebCore {
 
 class PLATFORM_EXPORT Canvas2DLayerBridge : public blink::WebExternalTextureLayerClient, public SkDeferredCanvas::NotificationClient, public DoublyLinkedListNode<Canvas2DLayerBridge>, public RefCounted<Canvas2DLayerBridge> {
     WTF_MAKE_NONCOPYABLE(Canvas2DLayerBridge);
 public:
     static PassRefPtr<Canvas2DLayerBridge> create(const IntSize&, OpacityMode, int msaaSampleCount);
+
     virtual ~Canvas2DLayerBridge();
 
     // blink::WebExternalTextureLayerClient implementation.
     virtual blink::WebGraphicsContext3D* context() OVERRIDE;
     virtual bool prepareMailbox(blink::WebExternalTextureMailbox*, blink::WebExternalBitmap*) OVERRIDE;
     virtual void mailboxReleased(const blink::WebExternalTextureMailbox&) OVERRIDE;
 
     // SkDeferredCanvas::NotificationClient implementation
     virtual void prepareForDraw() OVERRIDE;
     virtual void storageAllocatedForRecordingChanged(size_t) OVERRIDE;
     virtual void flushedDrawCommands() OVERRIDE;
     virtual void skippedPendingDrawCommands() OVERRIDE;
 
     // ImageBufferSurface implementation
     void willUse();
     SkCanvas* canvas() const { return m_canvas.get(); }
     bool isValid();
     blink::WebLayer* layer() const;
     Platform3DObject getBackingTexture();
     bool isAccelerated() const { return true; }
+    void setIsHidden(bool);
 
     // Methods used by Canvas2DLayerManager
     virtual size_t freeMemoryIfPossible(size_t); // virtual for mocking
     virtual void flush(); // virtual for mocking
     virtual size_t storageAllocatedForRecording(); // virtual for faking
-    size_t bytesAllocated() const {return m_bytesAllocated;}
+    size_t bytesAllocated() const { return m_bytesAllocated; }
     void limitPendingFrames();
+    void freeReleasedMailbox();
+    bool hasReleasedMailbox() const { return m_releasedMailboxInfo; };
+    void freeTransientResources();
+    bool hasTransientResources() const;
+    bool isHidden() { return m_isHidden; }
 
     void beginDestruction();
 
 protected:
     Canvas2DLayerBridge(PassRefPtr<GraphicsContext3D>, PassOwnPtr<SkDeferredCanvas>, int, OpacityMode);
     void setRateLimitingEnabled(bool);
+    bool releasedMailboxHasExpired();
 
     OwnPtr<SkDeferredCanvas> m_canvas;
     OwnPtr<blink::WebExternalTextureLayer> m_layer;
     RefPtr<GraphicsContext3D> m_context;
     int m_msaaSampleCount;
     size_t m_bytesAllocated;
     bool m_didRecordDrawCommand;
     bool m_surfaceIsValid;
     int m_framesPending;
+    int m_framesSinceMailboxRelease;
     bool m_destructionInProgress;
     bool m_rateLimitingEnabled;
+    bool m_isHidden;
 
     friend class WTF::DoublyLinkedListNode<Canvas2DLayerBridge>;
     friend class ::Canvas2DLayerBridgeTest;
     Canvas2DLayerBridge* m_next;
     Canvas2DLayerBridge* m_prev;
 
     enum MailboxStatus {
         MailboxInUse,
         MailboxReleased,
         MailboxAvailable,
     };
 
     struct MailboxInfo {
         blink::WebExternalTextureMailbox m_mailbox;
-        SkAutoTUnref<SkImage> m_image;
+        RefPtr<SkImage> m_image;
         MailboxStatus m_status;
         RefPtr<Canvas2DLayerBridge> m_parentLayerBridge;
 
         MailboxInfo(const MailboxInfo&);
         MailboxInfo() {}
     };
     MailboxInfo* createMailboxInfo();
 
     uint32_t m_lastImageId;
     Vector<MailboxInfo> m_mailboxes;
+    MailboxInfo* m_releasedMailboxInfo;
 };
 }
 #endif