Make sure gin Handles exist before using them

content/shell/renderer/test_runner/accessibility_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/test_runner/accessibility_controller.h"
 
 #include "gin/handle.h"
 #include "gin/object_template_builder.h"
 #include "gin/wrappable.h"
 #include "third_party/WebKit/public/web/WebElement.h"
@@ skipping 43 matching lines @@
   v8::HandleScope handle_scope(isolate);
   v8::Handle<v8::Context> context = frame->mainWorldScriptContext();
   if (context.IsEmpty())
     return;
 
   v8::Context::Scope context_scope(context);
 
   gin::Handle<AccessibilityControllerBindings> bindings =
       gin::CreateHandle(isolate,
                         new AccessibilityControllerBindings(controller));
+  if (bindings.IsEmpty())
+    return;
   v8::Handle<v8::Object> global = context->Global();
   global->Set(gin::StringToV8(isolate, "accessibilityController"),
               bindings.ToV8());
 }
 
 AccessibilityControllerBindings::AccessibilityControllerBindings(
     base::WeakPtr<AccessibilityController> controller)
   : controller_(controller) {
 }
 
@@ skipping 192 matching lines @@
     v8::Handle<v8::Object> result =
         FindAccessibleElementByIdRecursive(obj.childAt(i), id);
     if (*result)
       return result;
   }
 
   return v8::Handle<v8::Object>();
 }
 
 }  // namespace content