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

ui/gl/gl_surface_win.cc

Index: ui/gl/gl_surface_win.cc
diff --git a/ui/gl/gl_surface_win.cc b/ui/gl/gl_surface_win.cc
index 000110368d94a0cbe547213979675b1fcffef10c..3cde3ea9c7645ffd1dd9d20cf5ae19f603ccd9be 100644
--- a/ui/gl/gl_surface_win.cc
+++ b/ui/gl/gl_surface_win.cc
@@ -25,6 +25,15 @@
 #define EGL_D3D11_ELSE_D3D9_DISPLAY_ANGLE \
   reinterpret_cast<EGLNativeDisplayType>(-2)
 #endif
+#if !defined(EGL_PLATFORM_ANGLE_ANGLE)
+#define EGL_PLATFORM_ANGLE_ANGLE 0x3201
+#endif
+#if !defined(EGL_PLATFORM_ANGLE_TYPE_ANGLE)
+#define EGL_PLATFORM_ANGLE_TYPE_ANGLE 0x3202
+#endif
+#if !defined(EGL_PLATFORM_ANGLE_TYPE_D3D11_WARP_ANGLE)
+#define EGL_PLATFORM_ANGLE_TYPE_D3D11_WARP_ANGLE 0x3206
+#endif
 
 namespace gfx {
 
@@ -294,10 +303,10 @@ scoped_refptr<GLSurface> GLSurface::CreateOffscreenGLSurface(
 }
 
 EGLNativeDisplayType GetPlatformDefaultEGLNativeDisplay() {
-  if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kDisableD3D11))
-    return EGL_D3D11_ELSE_D3D9_DISPLAY_ANGLE;
-
-  return EGL_DEFAULT_DISPLAY;
+  if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kDisableD3D11) ||
+      CommandLine::ForCurrentProcess()->HasSwitch(switches::kUseWarp))
+    return GetDC(NULL);

[Ken Russell (switch to Gerrit), 2014/09/02 23:57:29]

Is GetDC(NULL) the correct return value when --disable-d3d11 is passed? How does
the behavior differ compared to the previous return value of
EGL_DEFAULT_DISPLAY?

[luken, 2014/09/03 00:58:07]

It turns out that ANGLE always wants a valid DeviceContext passed in as the
EGLNativeDisplayType argument to eglGetDisplay(), but the ANGLE code isn't
enforcing the validity check on the DC for that function call. It is, however,
enforcing that validity check for eglGetDisplayEXT(), which we now call in the
case for warp. If you don't specify a platform type you get the default display
which is D3D9. So in the case of disabling d3d11 we are still requesting the
"default" D3D9 display, but in a slightly less invalid way.

+  return EGL_D3D11_ELSE_D3D9_DISPLAY_ANGLE;
 }
 
 }  // namespace gfx