Bug 1172796 - Part 2: Add write-only flag for origin-clean check. r=roc

--HG--
extra : commitid : 2PNCCwc1czh

dom/canvas/OffscreenCanvas.cpp

@@ -24,12 +24,13 @@ namespace dom {
 OffscreenCanvasCloneData::OffscreenCanvasCloneData(layers::AsyncCanvasRenderer* aRenderer,
                                                    uint32_t aWidth, uint32_t aHeight,
                                                    layers::LayersBackend aCompositorBackend,
-                                                   bool aNeutered)
+                                                   bool aNeutered, bool aIsWriteOnly)
   : mRenderer(aRenderer)
   , mWidth(aWidth)
   , mHeight(aHeight)
   , mCompositorBackendType(aCompositorBackend)
   , mNeutered(aNeutered)
+  , mIsWriteOnly(aIsWriteOnly)
 {
 }
 
@@ -43,6 +44,7 @@ OffscreenCanvas::OffscreenCanvas(uint32_t aWidth,
                                  layers::AsyncCanvasRenderer* aRenderer)
   : mAttrDirty(false)
   , mNeutered(false)
+  , mIsWriteOnly(false)
   , mWidth(aWidth)
   , mHeight(aHeight)
   , mCompositorBackendType(aCompositorBackend)
@@ -191,7 +193,7 @@ OffscreenCanvasCloneData*
 OffscreenCanvas::ToCloneData()
 {
   return new OffscreenCanvasCloneData(mCanvasRenderer, mWidth, mHeight,
-                                      mCompositorBackendType, mNeutered);
+                                      mCompositorBackendType, mNeutered, mIsWriteOnly);
 }
 
 /* static */ already_AddRefed<OffscreenCanvas>

dom/canvas/OffscreenCanvas.h

@@ -35,7 +35,7 @@ struct OffscreenCanvasCloneData final
   OffscreenCanvasCloneData(layers::AsyncCanvasRenderer* aRenderer,
                            uint32_t aWidth, uint32_t aHeight,
                            layers::LayersBackend aCompositorBackend,
-                           bool aNeutered);
+                           bool aNeutered, bool aIsWriteOnly);
   ~OffscreenCanvasCloneData();
 
   RefPtr<layers::AsyncCanvasRenderer> mRenderer;
@@ -43,6 +43,7 @@ struct OffscreenCanvasCloneData final
   uint32_t mHeight;
   layers::LayersBackend mCompositorBackendType;
   bool mNeutered;
+  bool mIsWriteOnly;
 };
 
 class OffscreenCanvas final : public DOMEventTargetHelper
@@ -147,6 +148,16 @@ public:
     return mNeutered;
   }
 
+  void SetWriteOnly()
+  {
+    mIsWriteOnly = true;
+  }
+
+  bool IsWriteOnly() const
+  {
+    return mIsWriteOnly;
+  }
+
   layers::LayersBackend GetCompositorBackendType() const
   {
     return mCompositorBackendType;
@@ -164,6 +175,7 @@ private:
 
   bool mAttrDirty;
   bool mNeutered;
+  bool mIsWriteOnly;
 
   uint32_t mWidth;
   uint32_t mHeight;

dom/html/HTMLCanvasElement.cpp

@@ -783,6 +783,10 @@ HTMLCanvasElement::TransferControlToOffscreen(ErrorResult& aRv)
                                            sz.height,
                                            GetCompositorBackendType(),
                                            renderer);
+    if (mWriteOnly) {
+      mOffscreenCanvas->SetWriteOnly();
+    }
+
     if (!mContextObserver) {
       mContextObserver = new HTMLCanvasElementObserver(this);
     }