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 23 matching lines @@
 #include "platform/PlatformExport.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/graphics/GraphicsTypes3D.h"
 #include "platform/graphics/gpu/WebGLImageConversion.h"
 #include "public/platform/WebExternalTextureLayerClient.h"
 #include "public/platform/WebExternalTextureMailbox.h"
 #include "public/platform/WebGraphicsContext3D.h"
 #include "third_party/khronos/GLES2/gl2.h"
 #include "third_party/khronos/GLES2/gl2ext.h"
 #include "third_party/skia/include/core/SkBitmap.h"
+#include "wtf/Deque.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 class WebExternalBitmap;
 class WebExternalTextureLayer;
 class WebGraphicsContext3D;
 class WebLayer;
 }
@@ skipping 12 matching lines @@
     virtual IntSize oldestContextSize() = 0;
 };
 
 // Manages a rendering target (framebuffer + attachment) for a canvas.  Can publish its rendering
 // results to a blink::WebLayer for compositing.
 class PLATFORM_EXPORT DrawingBuffer : public RefCounted<DrawingBuffer>, public blink::WebExternalTextureLayerClient  {
     struct MailboxInfo : public RefCounted<MailboxInfo> {
         blink::WebExternalTextureMailbox mailbox;
         unsigned textureId;
         IntSize size;
+        // This keeps the parent drawing buffer alive as long as the compositor is
+        // referring to one of the mailboxes DrawingBuffer produced. The parent drawing buffer is
+        // cleared when the compositor returns the mailbox. See mailboxReleased().
+        RefPtr<DrawingBuffer> m_parentDrawingBuffer;
     };
 public:
     enum PreserveDrawingBuffer {
         Preserve,
         Discard
     };
 
     static PassRefPtr<DrawingBuffer> create(PassOwnPtr<blink::WebGraphicsContext3D>, const IntSize&, PreserveDrawingBuffer, PassRefPtr<ContextEvictionManager>);
 
     virtual ~DrawingBuffer();
 
+    // Destruction will be completed after all mailboxes are released.
+    void beginDestruction();
+
     // 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.
     static IntSize adjustSize(const IntSize& desiredSize, const IntSize& curSize, int maxTextureSize);
     bool reset(const IntSize&);
     void bind();
     IntSize size() const { return m_size; }
 
@@ skipping 35 matching lines @@
 
     // Destroys the TEXTURE_2D binding for the owned context
     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:
+protected: // For unittests
     DrawingBuffer(
         PassOwnPtr<blink::WebGraphicsContext3D>,
         PassOwnPtr<Extensions3DUtil>,
         bool multisampleExtensionSupported,
         bool packedDepthStencilExtensionSupported, PreserveDrawingBuffer, PassRefPtr<ContextEvictionManager>);
 
     bool initialize(const IntSize&);
-    void releaseResources();
+
+private:
+    void mailboxReleasedWhileDestructionInProgress(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();
 
     void clearPlatformLayer();
 
     PassRefPtr<MailboxInfo> recycledMailbox();
     PassRefPtr<MailboxInfo> createNewMailbox(unsigned);
+    void deleteMailbox(const blink::WebExternalTextureMailbox&);
 
     // Updates the current size of the buffer, ensuring that s_currentResourceUsePixels is updated.
     void setSize(const IntSize& size);
 
     // Calculates the difference in pixels between the current buffer size and the proposed size.
     static int pixelDelta(const IntSize& newSize, const IntSize& curSize);
 
     // Given the desired buffer size, provides the largest dimensions that will fit in the pixel budget
     // Returns true if the buffer will only fit if the oldest WebGL context is forcibly lost
     IntSize adjustSizeWithContextEviction(const IntSize&, bool& evictContext);
@@ skipping 59 matching lines @@
 
     MultisampleMode m_multisampleMode;
 
     blink::WebGraphicsContext3D::Attributes m_attributes;
     unsigned m_internalColorFormat;
     unsigned m_colorFormat;
     unsigned m_internalRenderbufferFormat;
     int m_maxTextureSize;
     int m_sampleCount;
     int m_packAlignment;
+    bool m_destructionInProgress;
 
     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;
+    // Mailboxes that were released by the compositor can be used again by this DrawingBuffer.
+    Deque<blink::WebExternalTextureMailbox> m_recycledMailboxQueue;
 
     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