Update to Chromium revision 6e53600d (#386251)

- Remove |accept_lang| parameter from CefJSDialogHandler::OnJSDialog
  and CefFormatUrlForSecurityDisplay (see https://crbug.com/336973#c36).
- Remove remaining NPAPI-related code including functions from
  cef_web_plugin.h (see https://crbug.com/493212#c55).
- Mac: 10.7+ deployment target is now required for client applications.
- Mac: Remove CefBrowserHost::SetWindowVisibility (issue #1375). No
  replacement is required for windowed rendering. Use WasHidden for
  off-screen rendering.
- Windows: Visual Studio 2015 Update 2 is now required when building
  CEF/Chromium.

libcef/browser/menu_model_impl.h

@@ -12,7 +12,6 @@
 #include "include/cef_menu_model.h"
 #include "include/cef_menu_model_delegate.h"
 
-#include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
 #include "base/threading/platform_thread.h"
 #include "ui/base/models/menu_model.h"
@@ -172,7 +171,7 @@ class CefMenuModelImpl : public CefMenuModel {
   CefRefPtr<CefMenuModelDelegate> menu_model_delegate_;
 
   ItemVector items_;
-  scoped_ptr<ui::MenuModel> model_;
+  std::unique_ptr<ui::MenuModel> model_;
 
   // Observers that want to be notified of changes to this object.
   base::ObserverList<Observer> observers_;