diff --git a/docshell/base/LoadContext.cpp b/docshell/base/LoadContext.cpp
index f08e049a0aa4..3a2ea33e0abe 100644
--- a/docshell/base/LoadContext.cpp
+++ b/docshell/base/LoadContext.cpp
@@ -7,7 +7,34 @@
 #include "mozilla/Assertions.h"
 #include "mozilla/BasePrincipal.h"
 #include "mozilla/LoadContext.h"
+#include "mozilla/dom/ScriptSettings.h" // for AutoJSAPI
+#include "nsContentUtils.h"
+#include "xpcpublic.h"
 
+bool
+nsILoadContext::GetOriginAttributes(mozilla::DocShellOriginAttributes& aAttrs)
+{
+  mozilla::dom::AutoJSAPI jsapi;
+  bool ok = jsapi.Init(xpc::PrivilegedJunkScope());
+  NS_ENSURE_TRUE(ok, false);
+  JS::Rooted<JS::Value> v(jsapi.cx());
+  nsresult rv = GetOriginAttributes(&v);
+  NS_ENSURE_SUCCESS(rv, false);
+  NS_ENSURE_TRUE(v.isObject(), false);
+  JS::Rooted<JSObject*> obj(jsapi.cx(), &v.toObject());
+
+  // If we're JS-implemented, the object will be left in a different (System-Principaled)
+  // scope, so we may need to enter its compartment.
+  MOZ_ASSERT(nsContentUtils::IsSystemPrincipal(nsContentUtils::ObjectPrincipal(obj)));
+  JSAutoCompartment ac(jsapi.cx(), obj);
+
+  mozilla::DocShellOriginAttributes attrs;
+  ok = attrs.Init(jsapi.cx(), v);
+  NS_ENSURE_TRUE(ok, false);
+  aAttrs = attrs;
+  return true;
+}
+  
 namespace mozilla {
 
 NS_IMPL_ISUPPORTS(LoadContext, nsILoadContext, nsIInterfaceRequestor)
diff --git a/docshell/base/nsILoadContext.idl b/docshell/base/nsILoadContext.idl
index bbdea31dd791..b4badd627b07 100644
--- a/docshell/base/nsILoadContext.idl
+++ b/docshell/base/nsILoadContext.idl
@@ -12,9 +12,6 @@ interface nsIDOMElement;
 %{C++
 #ifdef MOZILLA_INTERNAL_API
 #include "mozilla/BasePrincipal.h" // for DocShellOriginAttributes
-#include "mozilla/dom/ScriptSettings.h" // for AutoJSAPI
-#include "xpcpublic.h" // for PrivilegedJunkScope
-#include "nsContentUtils.h" // for IsSystemPrincipal
 #endif
 %}
 
@@ -23,7 +20,7 @@ interface nsIDOMElement;
  * can be queried for various information about where the load is
  * happening.
  */
-[scriptable, uuid(96014778-d30b-4fee-8902-a3481788907b)]
+[scriptable, uuid(c71ef717-8fb9-425e-98ef-aef5894890f8)]
 interface nsILoadContext : nsISupports
 {
   /**
@@ -139,30 +136,10 @@ interface nsILoadContext : nsISupports
 #ifdef MOZILLA_INTERNAL_API
   /**
    * The C++ getter for origin attributes.
+   *
+   * Defined in LoadContext.cpp
    */
-  bool GetOriginAttributes(mozilla::DocShellOriginAttributes& aAttrs)
-  {
-    mozilla::dom::AutoJSAPI jsapi;
-    bool ok = jsapi.Init(xpc::PrivilegedJunkScope());
-    NS_ENSURE_TRUE(ok, false);
-    JS::Rooted<JS::Value> v(jsapi.cx());
-    nsresult rv = GetOriginAttributes(&v);
-    NS_ENSURE_SUCCESS(rv, false);
-    NS_ENSURE_TRUE(v.isObject(), false);
-    JS::Rooted<JSObject*> obj(jsapi.cx(), &v.toObject());
-
-    // If we're JS-implemented, the object will be left in a different (System-Principaled)
-    // scope, so we may need to enter its compartment.
-    MOZ_ASSERT(nsContentUtils::IsSystemPrincipal(nsContentUtils::ObjectPrincipal(obj)));
-    JSAutoCompartment ac(jsapi.cx(), obj);
-
-    mozilla::DocShellOriginAttributes attrs;
-    ok = attrs.Init(jsapi.cx(), v);
-    NS_ENSURE_TRUE(ok, false);
-    aAttrs = attrs;
-    return true;
-  }
-
+  bool GetOriginAttributes(mozilla::DocShellOriginAttributes& aAttrs);
 #endif
 %}
 };