Introduce RootWindowProperty for RootWindow's properties

ash/root_window_property.h

+// Copyright 2013 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 ASH_WM_ROOT_WINDOW_PROPERTY_H_
+#define ASH_WM_ROOT_WINDOW_PROPERTY_H_
+
+#include "ash/ash_export.h"
+#include "base/basictypes.h"
+
+namespace aura {
+class RootWindow;
+}
+
+namespace ash {
+namespace internal {
+
+class RootWindowController;
+
+struct RootWindowProperty {

[James Cook, 2013/08/30 00:06:36]

Should this be RootWindowProperties because it contains multiple properties?  Or
maybe RootWindowConfiguration or RootWindowSettings?

I think the latter names might be better, since this doesn't actually store
window properties in the aura::WindowProperty sense.

Also, this struct should have a comment telling why it should be used instead of
general window properties.

[oshima, 2013/08/30 05:38:33]

I thought about RootWindowProperties, but I picked RootWindowProperty to see
what you think :) RootWindowSettings sounds a bit odd to me, but probably
because I'm not native speaker.

Here are all candidates including ones I thought of:

RootWindowAshInfo
RootWindowSettings
RootWindowExtraInfo
RootWindowProperties
RootWindowConfiguration

Let me know your pick.

[James Cook, 2013/08/30 16:26:25]

I like RootWindowSettings the best.  (Yeah, it's a little weird, but I really
want to avoid the word Properties.)

Also, this struct neeeds a comment.

+  RootWindowProperty();
+
+  // Indicate if the window in the active workspace should
+  // use the transparent "solo-window" header style.
+  bool solo_window_header;
+
+  // ID of the display associated with the root window.
+  int64 display_id;
+
+  // RootWindowController for the root window. This may be NULL
+  // for the root window used for mirroring.
+  RootWindowController* controller;
+};
+
+// Returns the RootWindowProperty for |root|. It automatically creates
+// new instance of the |root| does not exist and never returns NULL.

[James Cook, 2013/08/30 00:06:36]

of -> if

[oshima, 2013/08/30 05:38:33]

Done.

+ASH_EXPORT RootWindowProperty* GetRootWindowProperty(aura::RootWindow* root);
+
+// Returns the RootWindowProperty for const |root|. This may return NULL.

[James Cook, 2013/08/30 00:06:36]

Should this version just cast away the const and never return NULL?  It seems
like it might be hard for a caller to know which version they are calling and
hence whether or not to check for NULL.

[oshima, 2013/08/30 05:38:33]

I added InitRootWindowProperty instead to explicitly initialize the property.

+ASH_EXPORT const RootWindowProperty*
+GetRootWindowProperty(const aura::RootWindow* root);
+
+}  // namespace internal
+}  // namespace ash
+
+#endif  // ASH_WM_ROOT_WINDOW_PROPERTY_H_