Add better support for RGBA_4444 textures.

ui/compositor/compositor_switches.cc

 // Copyright (c) 2012 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 "ui/compositor/compositor_switches.h"
 
 #include "base/command_line.h"
 
 namespace switches {
 
 // Enable compositing individual elements via hardware overlays when
 // permitted by device.
 const char kEnableHardwareOverlays[] = "enable-hardware-overlays";
 
 // Forces tests to produce pixel output when they normally wouldn't.
 const char kEnablePixelOutputInTests[] = "enable-pixel-output-in-tests";
 
 const char kUIDisableThreadedCompositing[] = "ui-disable-threaded-compositing";
 
 const char kUIEnableCompositorAnimationTimelines[] =
     "ui-enable-compositor-animation-timelines";
 
+const char kUIEnableRGBA4444Textures[] = "ui-enable-rgba-4444-textures";
+
 const char kUIEnableZeroCopy[] = "ui-enable-zero-copy";
 
 const char kUIShowPaintRects[] = "ui-show-paint-rects";
 
 }  // namespace switches
 
 namespace ui {
 
 bool IsUIZeroCopyEnabled() {
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
   return command_line.HasSwitch(switches::kUIEnableZeroCopy);
 }
 
 bool IsUIOneCopyEnabled() {
   // One-copy is on by default unless zero copy is enabled.
   return !IsUIZeroCopyEnabled();
 }
 
 }  // namespace ui