gl: Move platform-specific EGL code into separate files

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 71812de087e2a5d1eb4aacabb31b6f28acde7e37..c0a223b76082056c42a2175ce8254ac90d1a0e35 100644
--- a/ui/gl/gl_surface_win.cc
+++ b/ui/gl/gl_surface_win.cc
@@ -6,6 +6,7 @@
 
 #include <dwmapi.h>
 
+#include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ -20,6 +21,12 @@
 #include "ui/gl/gl_surface_stub.h"
 #include "ui/gl/gl_surface_wgl.h"
 
+// From ANGLE's egl/eglext.h.
+#if !defined(EGL_D3D11_ELSE_D3D9_DISPLAY_ANGLE)
+#define EGL_D3D11_ELSE_D3D9_DISPLAY_ANGLE \
+  reinterpret_cast<EGLNativeDisplayType>(-2)
+#endif
+
 namespace gfx {
 
 // This OSMesa GL surface can use GDI to swap the contents of the buffer to a
@@ -287,4 +294,11 @@ scoped_refptr<GLSurface> GLSurface::CreateOffscreenGLSurface(
   }
 }
 
+EGLNativeDisplayType GetPlatformDefaultEGLNativeDisplay() {
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kDisableD3D11))
+    return EGL_D3D11_ELSE_D3D9_DISPLAY_ANGLE;
+
+  return EGL_DEFAULT_DISPLAY;
+}
+
 }  // namespace gfx