Add new gpu driver bug workaround DISABLE_TRANSPARENT_VISUALS

ui/gfx/x/x11_switches.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 "build/build_config.h"
 #include "ui/gfx/x/x11_switches.h"
 
 namespace switches {
 
 #if !defined(OS_CHROMEOS)
-// When enabled, tries to get a transparent X11 visual so that we can have
-// per-pixel alpha in windows.
-//
-// TODO(erg): Remove this switch once we've stabilized the code
-// path. http://crbug.com/369209
-const char kEnableTransparentVisuals[] = "enable-transparent-visuals";
-
 // Color bit depth of the main window created in the browser process and matches
 // XWindowAttributes.depth.
 const char kWindowDepth[] = "window-depth";
 
 // Which X11 display to connect to. Emulates the GTK+ "--display=" command line
 // argument.
 const char kX11Display[] = "display";
 
 // A VisualID that supports the requested window depth.
 const char kX11VisualID[] = "x11-visual-id";
 #endif
 
 }  // namespace switches