mac: Use IOSurfaces in Canvas2DLayerBridge.

third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h

Index: third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h
diff --git a/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h b/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h
index d55007aa9dd728032874a5a899a88edda01c19b8..f3d56a8dad469c999b944620116a70d26dea520c 100644
--- a/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h
+++ b/third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h
@@ -132,6 +132,11 @@ private:
         RefPtr<SkImage> m_image;
         RefPtr<Canvas2DLayerBridge> m_parentLayerBridge;
 
+        // If this mailbox wraps an IOSurface-backed texture, the ids of the
+        // CHROMIUM image and the texture.
+        GLuint m_CHROMIUMImageId = 0;

[Justin Novosad, 2016/03/02 16:33:45]

Can we use "#if OS(MACOSX)" for this (and the code that uses it)?

+        GLuint m_textureId = 0;
+
         MailboxInfo(const MailboxInfo&);
         MailboxInfo() {}
     };
@@ -154,6 +159,18 @@ private:
     // Returns the GL filter associated with |m_filterQuality|.
     GLenum getGLFilter();
 
+    // Creates an IOSurface-backed texture. Copies |image| into the texture.
+    // Prepares a mailbox from the texture. Stores all information in a newly
+    // created MailboxInfo, which resides in |m_mailboxes|. Returns whether the
+    // mailbox was successfully prepared. |mailbox| is an out parameter only
+    // populated on success.
+    bool prepareIOSurfaceMailboxFromImage(RefPtr<SkImage>&, WebExternalTextureMailbox*);
+
+    // Creates an IOSurface-backed texture. Returns whether the texture ewas
+    // successfully created. |texture| and |imageId| are out parameters. The
+    // caller takes ownership of both the texture and the image.
+    bool createIOSurfaceBackedTexture(GLuint* texture, GLuint* imageId);
+
     // Prepends a new MailboxInfo object to |m_mailboxes|, and returns a
     // reference. The reference is no longer valid after |m_mailboxes| is
     // mutated.