Add context to gfx::Screen calls in support of simultaneous desktop+ash

ui/gfx/screen_type_delegate.h

Index: ui/gfx/screen_type_delegate.h
diff --git a/ui/gfx/screen_type_delegate.h b/ui/gfx/screen_type_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..4ff9ea351a001a25c7424129b3c58b450eaae64e
--- /dev/null
+++ b/ui/gfx/screen_type_delegate.h
@@ -0,0 +1,29 @@
+// Copyright 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.
+
+#ifndef UI_GFX_SCREEN_TYPE_DELEGATE_H_
+#define UI_GFX_SCREEN_TYPE_DELEGATE_H_
+
+#include "ui/gfx/native_widget_types.h"
+
+namespace gfx {
+
+enum UI_EXPORT ScreenType {
+  SCREEN_TYPE_NATIVE,

[oshima, 2012/10/10 17:58:23]

SCREEN_TYPE_NATIVE = 0,  (assuming that's what you expect)

[scottmg, 2012/10/10 19:04:47]

Done.

+  SCREEN_TYPE_ALTERNATE,
+  SCREEN_TYPE_LAST = SCREEN_TYPE_ALTERNATE,
+  SCREEN_TYPE_INVALID,

[oshima, 2012/10/10 17:58:23]

Do you need this _INVALID? (looks like this isn't used anywhere?)

[scottmg, 2012/10/10 19:04:47]

Done.

+};
+
+class UI_EXPORT ScreenTypeDelegate {
+ public:
+  virtual ~ScreenTypeDelegate() {}
+
+  // Determines which ScreenType a given |view| belongs to.
+  virtual ScreenType GetScreenTypeForNativeView(NativeView view) = 0;
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_SCREEN_TYPE_DELEGATE_H_