Fix a crash in TestingAutomationProvider::GetTabInfo on ChromeOS.

chrome/browser/automation/testing_automation_provider.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/browser/automation/testing_automation_provider.h"
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 6650 matching lines @@
 
 void TestingAutomationProvider::GetTabInfo(
     DictionaryValue* args,
     IPC::Message* reply_message) {
   AutomationJSONReply reply(this, reply_message);
   Browser* browser;
   WebContents* tab;
   std::string error;
   if (GetBrowserAndTabFromJSONArgs(args, &browser, &tab, &error)) {
     NavigationEntry* entry = tab->GetController().GetActiveEntry();
+    if (!entry) {
+      reply.SendError("Unable to get active navigation entry");
+      return;
+    }
     DictionaryValue dict;
     dict.SetString("title", entry->GetTitleForDisplay(""));
     dict.SetString("url", entry->GetVirtualURL().spec());
     reply.SendSuccess(&dict);
   } else {
     reply.SendError(error);
   }
 }
 
 void TestingAutomationProvider::GetTabCountJSON(
@@ skipping 562 matching lines @@
 void TestingAutomationProvider::OnRemoveProvider() {
   if (g_browser_process)
     g_browser_process->GetAutomationProviderList()->RemoveProvider(this);
 }
 
 void TestingAutomationProvider::EnsureTabSelected(Browser* browser,
                                                   WebContents* tab) {
   if (chrome::GetActiveWebContents(browser) != tab)
     chrome::ActivateTabAt(browser, chrome::GetIndexOfTab(browser, tab), true);
 }