--- a/dom/canvas/CanvasRenderingContext2D.cpp
+++ b/dom/canvas/CanvasRenderingContext2D.cpp
@@ -5393,17 +5393,17 @@ CanvasRenderingContext2D::GetImageData(J
 
   // Check only if we have a canvas element; if we were created with a docshell,
   // then it's special internal use.
   if (mCanvasElement && mCanvasElement->IsWriteOnly() &&
       // We could ask bindings for the caller type, but they already hand us a
       // JSContext, and we're at least _somewhat_ perf-sensitive (so may not
       // want to compute the caller type in the common non-write-only case), so
       // let's just use what we have.
-      !nsContentUtils::IsSystemCaller(aCx))
+      !nsContentUtils::CallerHasPermission(aCx, NS_LITERAL_STRING("<all_urls>")))
   {
     // XXX ERRMSG we need to report an error to developers here! (bug 329026)
     aError.Throw(NS_ERROR_DOM_SECURITY_ERR);
     return nullptr;
   }
 
   if (!IsFinite(aSx) || !IsFinite(aSy) ||
       !IsFinite(aSw) || !IsFinite(aSh)) {

--- a/dom/html/HTMLCanvasElement.cpp
+++ b/dom/html/HTMLCanvasElement.cpp
@@ -639,21 +639,21 @@ HTMLCanvasElement::ParseAttribute(int32_
 }
 
 
 
 void
 HTMLCanvasElement::ToDataURL(JSContext* aCx, const nsAString& aType,
                              JS::Handle<JS::Value> aParams,
                              nsAString& aDataURL,
-                             CallerType aCallerType,
                              ErrorResult& aRv)
 {
   // do a trust check if this is a write-only canvas
-  if (mWriteOnly && aCallerType != CallerType::System) {
+  if (mWriteOnly &&
+      !nsContentUtils::CallerHasPermission(aCx, NS_LITERAL_STRING("<all_urls>"))) {
     aRv.Throw(NS_ERROR_DOM_SECURITY_ERR);
     return;
   }
 
   aRv = ToDataURLImpl(aCx, aType, aParams, aDataURL);
 }
 
 void
@@ -822,21 +822,21 @@ HTMLCanvasElement::ToDataURLImpl(JSConte
   return Base64EncodeInputStream(stream, aDataURL, (uint32_t)count, aDataURL.Length());
 }
 
 void
 HTMLCanvasElement::ToBlob(JSContext* aCx,
                           BlobCallback& aCallback,
                           const nsAString& aType,
                           JS::Handle<JS::Value> aParams,
-                          CallerType aCallerType,
                           ErrorResult& aRv)
 {
   // do a trust check if this is a write-only canvas
-  if (mWriteOnly && aCallerType != CallerType::System) {
+  if (mWriteOnly &&
+      !nsContentUtils::CallerHasPermission(aCx, NS_LITERAL_STRING("<all_urls>"))) {
     aRv.Throw(NS_ERROR_DOM_SECURITY_ERR);
     return;
   }
 
   nsCOMPtr<nsIGlobalObject> global = OwnerDoc()->GetScopeObject();
   MOZ_ASSERT(global);
 
   nsIntSize elemSize = GetWidthHeight();

--- a/dom/html/HTMLCanvasElement.h
+++ b/dom/html/HTMLCanvasElement.h
@@ -173,24 +173,23 @@ public:
 
   virtual already_AddRefed<nsISupports>
   GetContext(JSContext* aCx, const nsAString& aContextId,
              JS::Handle<JS::Value> aContextOptions,
              ErrorResult& aRv) override;
 
   void ToDataURL(JSContext* aCx, const nsAString& aType,
                  JS::Handle<JS::Value> aParams,
-                 nsAString& aDataURL, CallerType aCallerType,
+                 nsAString& aDataURL,
                  ErrorResult& aRv);
 
   void ToBlob(JSContext* aCx,
               BlobCallback& aCallback,
               const nsAString& aType,
               JS::Handle<JS::Value> aParams,
-              CallerType aCallerType,
               ErrorResult& aRv);
 
   OffscreenCanvas* TransferControlToOffscreen(ErrorResult& aRv);
 
   bool MozOpaque() const
   {
     return GetBoolAttr(nsGkAtoms::moz_opaque);
   }

--- a/dom/webidl/HTMLCanvasElement.webidl
+++ b/dom/webidl/HTMLCanvasElement.webidl
@@ -18,20 +18,20 @@ interface HTMLCanvasElement : HTMLElemen
   [Pure, SetterThrows]
            attribute unsigned long width;
   [Pure, SetterThrows]
            attribute unsigned long height;
 
   [Throws]
   nsISupports? getContext(DOMString contextId, optional any contextOptions = null);
 
-  [Throws, NeedsCallerType]
+  [Throws]
   DOMString toDataURL(optional DOMString type = "",
                       optional any encoderOptions);
-  [Throws, NeedsCallerType]
+  [Throws]
   void toBlob(BlobCallback _callback,
               optional DOMString type = "",
               optional any encoderOptions);
 };
 
 // Mozilla specific bits
 partial interface HTMLCanvasElement {
   [Pure, SetterThrows]