adds WARP support to Chromium, for Metro mode only, on Windows 8

ui/gl/gl_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/gl/gl_switches.h"
 #include "base/basictypes.h"
 
 namespace gfx {
 
 const char kGLImplementationDesktopName[]     = "desktop";
@@ skipping 38 matching lines @@
 // Indicates whether the dual GPU switching is supported or not.
 const char kSupportsDualGpus[]              = "supports-dual-gpus";
 
 // Flag used for Linux tests: for desktop GL bindings, try to load this GL
 // library first, but fall back to regular library if loading fails.
 const char kTestGLLib[]                     = "test-gl-lib";
 
 // Use hardware gpu, if available, for tests.
 const char kUseGpuInTests[] = "use-gpu-in-tests";
 
+// On Windows only: use the WARP software rasterizer in the GPU process.
+const char kUseWarp[] = "use-warp";
+
 // Disables GL drawing operations which produce pixel output. With this
 // the GL output will not be correct but tests will run faster.
 const char kDisableGLDrawingForTests[] = "disable-gl-drawing-for-tests";
 
 // Forces the use of OSMesa instead of hardware gpu.
 const char kOverrideUseGLWithOSMesaForTests[] =
     "override-use-gl-with-osmesa-for-tests";
 
 // This is the list of switches passed from this file that are passed from the
 // GpuProcessHost to the GPU Process. Add your switch to this list if you need
 // to read it in the GPU process, else don't add it.
 const char* kGLSwitchesCopiedFromGpuProcessHost[] = {
   kDisableGpuVsync,
   kDisableD3D11,
   kEnableGPUServiceLogging,
   kEnableGPUServiceTracing,
   kGpuNoContextLost,
   kDisableGLDrawingForTests,
   kOverrideUseGLWithOSMesaForTests,
+  kUseWarp
 };
 const int kGLSwitchesCopiedFromGpuProcessHostNumSwitches =
     arraysize(kGLSwitchesCopiedFromGpuProcessHost);
 
 }  // namespace switches