Fix for possible crashes due to pointer value being null

content/browser/accessibility/accessibility_ui.cc

 // Copyright (c) 2013 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/browser/accessibility/accessibility_ui.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/json/json_writer.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 48 matching lines @@
   target_data->SetInteger(kPidField, base::GetProcId(handle));
   target_data->SetString(kFaviconUrlField, favicon_url.spec());
   target_data->SetInteger(kAccessibilityModeField,
                           accessibility_mode);
   return target_data;
 }
 
 base::DictionaryValue* BuildTargetDescriptor(RenderViewHost* rvh) {
   WebContentsImpl* web_contents = static_cast<WebContentsImpl*>(
       WebContents::FromRenderViewHost(rvh));
-  AccessibilityMode accessibility_mode = web_contents->GetAccessibilityMode();
+  AccessibilityMode accessibility_mode = AccessibilityModeOff;
 
   std::string title;
   GURL url;
   GURL favicon_url;
   if (web_contents) {
     // TODO(nasko): Fix the following code to use a consistent set of data
     // across the URL, title, and favicon.
     url = web_contents->GetURL();
     title = base::UTF16ToUTF8(web_contents->GetTitle());
     NavigationController& controller = web_contents->GetController();
     NavigationEntry* entry = controller.GetVisibleEntry();
     if (entry != NULL && entry->GetURL().is_valid())
       favicon_url = entry->GetFavicon().url;
+    accessibility_mode = web_contents->GetAccessibilityMode();
   }
 
   return BuildTargetDescriptor(url,
                                title,
                                favicon_url,
                                rvh->GetProcess()->GetID(),
                                rvh->GetRoutingID(),
                                accessibility_mode);
 }
 
@@ skipping 139 matching lines @@
   formatter->SetFilters(filters);
   formatter->FormatAccessibilityTree(&accessibility_contents_utf16);
 
   result->Set("tree",
               new base::StringValue(
                   base::UTF16ToUTF8(accessibility_contents_utf16)));
   web_ui()->CallJavascriptFunction("accessibility.showTree", *(result.get()));
 }
 
 }  // namespace content