[Extensions] Check is_valid() in app bindings

chrome/renderer/extensions/app_bindings.cc

 // Copyright (c) 2012 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/extensions/app_bindings.h"
 
 #include "base/command_line.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_util.h"
@@ skipping 144 matching lines @@
   IPC_BEGIN_MESSAGE_MAP(AppBindings, message)
     IPC_MESSAGE_HANDLER(ExtensionMsg_GetAppInstallStateResponse,
                         OnAppInstallStateResponse)
     IPC_MESSAGE_UNHANDLED(CHECK(false) << "Unhandled IPC message")
   IPC_END_MESSAGE_MAP()
   return true;
 }
 
 void AppBindings::OnAppInstallStateResponse(
     const std::string& state, int callback_id) {
+  if (!is_valid())
+    return;
+
   v8::Isolate* isolate = context()->isolate();
   v8::HandleScope handle_scope(isolate);
   v8::Context::Scope context_scope(context()->v8_context());
   v8::Local<v8::Value> argv[] = {
     v8::String::NewFromUtf8(isolate, state.c_str()),
     v8::Integer::New(isolate, callback_id)
   };
   context()->module_system()->CallModuleMethod(
       "app", "onInstallStateResponse", arraysize(argv), argv);
 }
 
 }  // namespace extensions