Disable textfield's context menu in screen locker

chrome/browser/chromeos/login/screen_locker.cc

 // Copyright (c) 2011 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/chromeos/login/screen_locker.h"
 
 #include <X11/extensions/XTest.h>
 #include <X11/keysym.h>
 #include <gdk/gdkkeysyms.h>
 #include <gdk/gdkx.h>
@@ skipping 788 matching lines @@
   // Add the window to its own group so that its grab won't be stolen if
   // gtk_grab_add() gets called on behalf on a non-screen-locker widget (e.g.
   // a modal dialog) -- see http://crosbug.com/8999.  We intentionally do this
   // after calling ClearGtkGrab(), as want to be in the default window group
   // then so we can break any existing GTK grabs.
   GtkWindowGroup* window_group = gtk_window_group_new();
   gtk_window_group_add_window(window_group,
                               GTK_WINDOW(lock_window_->GetNativeView()));
   g_object_unref(window_group);
 
-  // Don't let X draw default background, which was causing flash on
-  // resume.
-  gdk_window_set_back_pixmap(lock_window_->GetNativeView()->window,
-                             NULL, false);
-  gdk_window_set_back_pixmap(lock_widget_->GetNativeView()->window,
-                             NULL, false);
   lock_window->set_toplevel_focus_widget(
       static_cast<views::WidgetGtk*>(lock_widget_->native_widget())->
           window_contents());
 
   // Create the SystemKeyEventListener so it can listen for system keyboard
   // messages regardless of focus while screen locked.
   SystemKeyEventListener::GetInstance();
 }
 
 void ScreenLocker::OnLoginFailure(const LoginFailure& error) {
@@ skipping 372 matching lines @@
 
 bool ScreenLocker::AcceleratorPressed(const views::Accelerator& accelerator) {
   if (!background_view_->IsScreenSaverVisible()) {
     StartScreenSaver();
     return true;
   }
   return false;
 }
 
 }  // namespace chromeos