Prepare GuestView for removing swapped out RenderFrame.

extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc

Index: extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc
diff --git a/extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc b/extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc
index 7eb129236551ca24185357a5af7054915f95d7a7..ee243bf6922e528e5461ab0762d662a64929378b 100644
--- a/extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc
+++ b/extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc
@@ -24,6 +24,7 @@
 #include "extensions/renderer/script_context.h"
 #include "third_party/WebKit/public/web/WebFrame.h"
 #include "third_party/WebKit/public/web/WebLocalFrame.h"
+#include "third_party/WebKit/public/web/WebRemoteFrame.h"
 #include "third_party/WebKit/public/web/WebScopedUserGesture.h"
 #include "third_party/WebKit/public/web/WebView.h"
 #include "v8/include/v8.h"
@@ -314,7 +315,15 @@ void GuestViewInternalCustomBindings::GetContentWindow(
     return;
 
   blink::WebFrame* frame = view->GetWebView()->mainFrame();
-  v8::Local<v8::Value> window = frame->mainWorldScriptContext()->Global();
+  // TODO(lazyboy,nasko): The WebLocalFrame branch is not used when running
+  // on top of out-of-process iframes. Remove it once the code is converted.
+  v8::Local<v8::Value> window;
+  if (frame->isWebLocalFrame()) {
+    window = frame->mainWorldScriptContext()->Global();
+  } else {
+    window =
+        frame->toWebRemoteFrame()->deprecatedMainWorldScriptContext()->Global();
+  }
   args.GetReturnValue().Set(window);
 }