Make sure gin Handles exist before using them

content/shell/renderer/gc_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 "content/shell/renderer/gc_controller.h"
 
 #include "gin/arguments.h"
 #include "gin/handle.h"
 #include "gin/object_template_builder.h"
 #include "third_party/WebKit/public/web/WebFrame.h"
 #include "third_party/WebKit/public/web/WebKit.h"
 #include "v8/include/v8.h"
 
 namespace content {
 
 gin::WrapperInfo GCController::kWrapperInfo = {gin::kEmbedderNativeGin};
 
 // static
 void GCController::Install(blink::WebFrame* frame) {
   v8::Isolate* isolate = blink::mainThreadIsolate();
   v8::HandleScope handle_scope(isolate);
   v8::Handle<v8::Context> context = frame->mainWorldScriptContext();
   if (context.IsEmpty())
     return;
 
   v8::Context::Scope context_scope(context);
 
   gin::Handle<GCController> controller =
       gin::CreateHandle(isolate, new GCController());
+  if (controller.IsEmpty())
+    return;
   v8::Handle<v8::Object> global = context->Global();
   global->Set(gin::StringToV8(isolate, "GCController"), controller.ToV8());
 }
 
 GCController::GCController() {}
 
 GCController::~GCController() {}
 
 gin::ObjectTemplateBuilder GCController::GetObjectTemplateBuilder(
     v8::Isolate* isolate) {
@@ skipping 21 matching lines @@
         v8::Isolate::kFullGarbageCollection);
   }
 }
 
 void GCController::MinorCollect(const gin::Arguments& args) {
   args.isolate()->RequestGarbageCollectionForTesting(
       v8::Isolate::kMinorGarbageCollection);
 }
 
 }  // namespace content