Throw security errors for attribute access on detached windows.

third_party/WebKit/Source/bindings/core/v8/BindingSecurity.cpp

Index: third_party/WebKit/Source/bindings/core/v8/BindingSecurity.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/BindingSecurity.cpp b/third_party/WebKit/Source/bindings/core/v8/BindingSecurity.cpp
index 516ef4dff5498d95b703de67ff7f23e7350fcaca..34ea4a8c9c93209ba95580505a6bad81add8ff39 100644
--- a/third_party/WebKit/Source/bindings/core/v8/BindingSecurity.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/BindingSecurity.cpp
@@ -254,21 +254,27 @@ bool BindingSecurity::shouldAllowNamedAccessTo(const DOMWindow* accessingWindow,
 
 void BindingSecurity::failedAccessCheckFor(v8::Isolate* isolate,
                                            const Frame* target) {
-  // TODO(dcheng): See if this null check can be removed or hoisted to a
-  // different location.
-  if (!target)
-    return;
-
-  DOMWindow* targetWindow = target->domWindow();
-
   // TODO(dcheng): Add ContextType, interface name, and property name as
   // arguments, so the generated exception can be more descriptive.
   ExceptionState exceptionState(isolate, ExceptionState::UnknownContext,
                                 nullptr, nullptr);
+
+  LocalDOMWindow* callingWindow = currentDOMWindow(isolate);
+  if (!target) {
+    const SecurityOrigin* activeOrigin =
+        callingWindow->document()->getSecurityOrigin();
+    String message = "Blocked a frame with origin \"" +
+                     activeOrigin->toString() +
+                     "\" from accessing a detached cross-origin frame";
+    exceptionState.throwSecurityError(message, message);
+    return;
+  }
+
+  DOMWindow* targetWindow = target->domWindow();
+
   exceptionState.throwSecurityError(
-      targetWindow->sanitizedCrossDomainAccessErrorMessage(
-          currentDOMWindow(isolate)),
-      targetWindow->crossDomainAccessErrorMessage(currentDOMWindow(isolate)));
+      targetWindow->sanitizedCrossDomainAccessErrorMessage(callingWindow),
+      targetWindow->crossDomainAccessErrorMessage(callingWindow));
 }
 
 }  // namespace blink