WebGL: Don't destroy mailbox textures in the destructor until they're released.

Source/platform/graphics/gpu/DrawingBuffer.h

 /*
  * Copyright (c) 2010, 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 61 matching lines @@
         blink::WebExternalTextureMailbox mailbox;
         unsigned textureId;
         IntSize size;
     };
 public:
     enum PreserveDrawingBuffer {
         Preserve,
         Discard
     };
 
-    static PassRefPtr<DrawingBuffer> create(blink::WebGraphicsContext3D*, const IntSize&, PreserveDrawingBuffer, PassRefPtr<ContextEvictionManager>);
+    static PassRefPtr<DrawingBuffer> create(PassOwnPtr<blink::WebGraphicsContext3D>, const IntSize&, PreserveDrawingBuffer, PassRefPtr<ContextEvictionManager>);
 
     virtual ~DrawingBuffer();
 
+    // Clear all resources from this object, as well as context. Called when context is destroyed
+    // to prevent invalid accesses to the resources.
+    void releaseResources();
+
     // Issues a glClear() on all framebuffers associated with this DrawingBuffer. The caller is responsible for
     // making the context current and setting the clear values and masks. Modifies the framebuffer binding.
     void clearFramebuffers(GLbitfield clearMask);
 
     // Given the desired buffer size, provides the largest dimensions that will fit in the pixel budget.
     IntSize adjustSize(const IntSize&);
     bool reset(const IntSize&);
     void bind();
     IntSize size() const { return m_size; }
 
@@ skipping 35 matching lines @@
 
     bool copyToPlatformTexture(blink::WebGraphicsContext3D*, Platform3DObject texture, GLenum internalFormat,
         GLenum destType, GLint level, bool premultiplyAlpha, bool flipY);
 
     void setPackAlignment(GLint param);
 
     void paintRenderingResultsToCanvas(ImageBuffer*);
     PassRefPtr<Uint8ClampedArray> paintRenderingResultsToImageData(int&, int&);
 
 private:
-    DrawingBuffer(blink::WebGraphicsContext3D*, bool multisampleExtensionSupported,
+    DrawingBuffer(PassOwnPtr<blink::WebGraphicsContext3D>, bool multisampleExtensionSupported,
                   bool packedDepthStencilExtensionSupported, PreserveDrawingBuffer, PassRefPtr<ContextEvictionManager>);
 
     bool initialize(const IntSize&);
-    // Clear all resources from this object, as well as context. Called when context is destroyed
-    // to prevent invalid accesses to the resources.
-    void releaseResources();
+    void releaseSelf(const blink::WebExternalTextureMailbox&);
 
     unsigned createColorTexture(const IntSize& size = IntSize());
     // Create the depth/stencil and multisample buffers, if needed.
     void createSecondaryBuffers();
     bool resizeFramebuffer(const IntSize&);
     bool resizeMultisampleFramebuffer(const IntSize&);
     void resizeDepthStencil(const IntSize&);
 
     // Bind to the m_framebufferBinding if it's not 0.
     void restoreFramebufferBinding();
@@ skipping 31 matching lines @@
     // Helper to texImage2D with pixel==0 case: pixels are initialized to 0.
     // By default, alignment is 4, the OpenGL default setting.
     void texImage2DResourceSafe(GLenum target, GLint level, GLenum internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, GLint alignment = 4);
 
     PreserveDrawingBuffer m_preserveDrawingBuffer;
     bool m_scissorEnabled;
     Platform3DObject m_texture2DBinding;
     Platform3DObject m_framebufferBinding;
     GLenum m_activeTextureUnit;
 
-    blink::WebGraphicsContext3D* m_context;
+    OwnPtr<blink::WebGraphicsContext3D> m_context;
     IntSize m_size;
     bool m_multisampleExtensionSupported;
     bool m_packedDepthStencilExtensionSupported;
     Platform3DObject m_fbo;
     // DrawingBuffer's output is double-buffered. m_colorBuffer is the back buffer.
     Platform3DObject m_colorBuffer;
     Platform3DObject m_frontColorBuffer;
 
     // This is used when we have OES_packed_depth_stencil.
     Platform3DObject m_depthStencilBuffer;
@@ skipping 20 matching lines @@
     int m_maxTextureSize;
     int m_sampleCount;
     int m_packAlignment;
 
     OwnPtr<blink::WebExternalTextureLayer> m_layer;
 
     // All of the mailboxes that this DrawingBuffer has ever created.
     Vector<RefPtr<MailboxInfo> > m_textureMailboxes;
     // Mailboxes that were released by the compositor and can be used again by this DrawingBuffer.
     Vector<RefPtr<MailboxInfo> > m_recycledMailboxes;
+    // This class will be destructed after all mailboxes are received.
+    RefPtr<DrawingBuffer> m_selfToWaitForMailboxes;
 
     RefPtr<ContextEvictionManager> m_contextEvictionManager;
 
     // If the width and height of the Canvas's backing store don't
     // match those that we were given in the most recent call to
     // reshape(), then we need an intermediate bitmap to read back the
     // frame buffer into. This seems to happen when CSS styles are
     // used to resize the Canvas.
     SkBitmap m_resizingBitmap;
 
     // Used to flip a bitmap vertically.
     Vector<uint8_t> m_scanline;
 };
 
 } // namespace WebCore
 
 #endif // DrawingBuffer_h