Speculative fix for ChromeWebViewGuestDelegate crash.

chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.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 "chrome/browser/guest_view/web_view/chrome_web_view_guest_delegate.h"
 
 #include "chrome/browser/extensions/chrome_extension_web_contents_observer.h"
 #include "chrome/browser/favicon/favicon_helper.h"
 #include "chrome/browser/profiles/profile.h"
@@ skipping 32 matching lines @@
 ChromeWebViewGuestDelegate::~ChromeWebViewGuestDelegate() {
 }
 
 bool ChromeWebViewGuestDelegate::HandleContextMenu(
     const content::ContextMenuParams& params) {
   ContextMenuDelegate* menu_delegate =
       ContextMenuDelegate::FromWebContents(guest_web_contents());
   DCHECK(menu_delegate);
 
   pending_menu_ = menu_delegate->BuildMenu(guest_web_contents(), params);
+  // It's possible for the returned menu to be null, so early out to avoid
+  // a crash. TODO(wjmaclean): find out why it's possible for this to happen
+  // in the first place, and if it's an error.
+  if (!pending_menu_)
+    return false;
 
   // Pass it to embedder.
   int request_id = ++pending_context_menu_request_id_;
   scoped_ptr<base::DictionaryValue> args(new base::DictionaryValue());
   scoped_ptr<base::ListValue> items =
       MenuModelToValue(pending_menu_->menu_model());
   args->Set(webview::kContextMenuItems, items.release());
   args->SetInteger(webview::kRequestId, request_id);
   web_view_guest()->DispatchEventToView(
       new GuestViewEvent(webview::kEventContextMenuShow, args.Pass()));
@@ skipping 109 matching lines @@
       chromeos::ACCESSIBILITY_TOGGLE_SPOKEN_FEEDBACK) {
     if (details.enabled)
       InjectChromeVoxIfNeeded(guest_web_contents()->GetRenderViewHost());
     else
       chromevox_injected_ = false;
   }
 }
 #endif
 
 }  // namespace extensions