Move MainWorldScriptContext accessor/method from WebFrame to WebLocalFrame.

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 77440eef9d697bf08d4e6f2522866feebbaa5d77..ddba6ea548e591494c3faa46be905ea96a6d52f4 100644
--- a/extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc
+++ b/extensions/renderer/guest_view/guest_view_internal_custom_bindings.cc
@@ -342,14 +342,7 @@ void GuestViewInternalCustomBindings::GetContentWindow(
     return;
 
   blink::WebFrame* frame = view->GetWebView()->MainFrame();
-  // 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.

[Devlin, 2017/06/09 18:56:40]

Is isolate extensions sufficient for this, or does this need to wait for full
isolation?

-  v8::Local<v8::Value> window;
-  if (frame->IsWebLocalFrame()) {
-    window = frame->MainWorldScriptContext()->Global();
-  } else {
-    window = frame->ToWebRemoteFrame()->GlobalProxy();
-  }
+  v8::Local<v8::Value> window = frame->GlobalProxy();
   args.GetReturnValue().Set(window);
 }