Make sure gin Handles exist before using them

chrome/renderer/net/net_error_page_controller.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/net/net_error_page_controller.h"
 
 #include "base/strings/string_piece.h"
 #include "chrome/renderer/net/net_error_helper.h"
 #include "content/public/renderer/render_frame.h"
 #include "gin/handle.h"
@@ skipping 10 matching lines @@
   v8::HandleScope handle_scope(isolate);
   v8::Handle<v8::Context> context =
       render_frame->GetWebFrame()->mainWorldScriptContext();
   if (context.IsEmpty())
     return;
 
   v8::Context::Scope context_scope(context);
 
   gin::Handle<NetErrorPageController> controller = gin::CreateHandle(
       isolate, new NetErrorPageController(render_frame));
+  if (controller.IsEmpty())
+    return;
+
   v8::Handle<v8::Object> global = context->Global();
   global->Set(gin::StringToV8(isolate, "errorPageController"),
               controller.ToV8());
 }
 
 bool NetErrorPageController::LoadStaleButtonClick() {
   if (!render_frame())
     return false;
 
   NetErrorHelper* net_error_helper =
@@ skipping 39 matching lines @@
              isolate)
       .SetMethod("loadStaleButtonClick",
                  &NetErrorPageController::LoadStaleButtonClick)
       .SetMethod("reloadButtonClick",
                  &NetErrorPageController::ReloadButtonClick)
       .SetMethod("moreButtonClick",
                  &NetErrorPageController::MoreButtonClick);
 }
 
 void NetErrorPageController::OnDestruct() {}