Start consolidating cross-port file selection code into ui/base/dialogs.

ui/base/dialogs/base_shell_dialog.h

Index: ui/base/dialogs/base_shell_dialog.h
diff --git a/chrome/browser/ui/base_shell_dialog.h b/ui/base/dialogs/base_shell_dialog.h
similarity index 79%
rename from chrome/browser/ui/base_shell_dialog.h
rename to ui/base/dialogs/base_shell_dialog.h
index 4a5a99c1ab2056f7625cf86a56f773a56036f568..e8a0579b46e5da594767a97d4799c33a1d8d5d08 100644
--- a/chrome/browser/ui/base_shell_dialog.h
+++ b/ui/base/dialogs/base_shell_dialog.h
@@ -2,12 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef CHROME_BROWSER_UI_BASE_SHELL_DIALOG_H_
-#define CHROME_BROWSER_UI_BASE_SHELL_DIALOG_H_
+#ifndef UI_BASE_DIALOGS_BASE_SHELL_DIALOG_H_
+#define UI_BASE_DIALOGS_BASE_SHELL_DIALOG_H_
 #pragma once
 
 #include "ui/gfx/native_widget_types.h"
 
+namespace ui {
+
 // A base class for shell dialogs.
 class BaseShellDialog {
  public:
@@ -23,4 +25,6 @@ class BaseShellDialog {
   virtual ~BaseShellDialog() {}
 };
 
-#endif  // CHROME_BROWSER_UI_BASE_SHELL_DIALOG_H_
+}  // namespace
+
+#endif  // UI_BASE_DIALOGS_BASE_SHELL_DIALOG_H_