Sort out build dependencies for LinuxUI.

ui/shell_dialogs/linux_shell_dialog.h

+// Copyright (c) 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 UI_SHELL_DIALOGS_LINUX_SHELL_DIALOG_H_
+#define UI_SHELL_DIALOGS_LINUX_SHELL_DIALOG_H_
+
+#include "ui/shell_dialogs/select_file_dialog.h"
+#include "ui/shell_dialogs/shell_dialogs_export.h"
+
+namespace ui {
+
+// An interface that lets different Linux platforms override the
+// CreateSelectFileDialog function declared here to return native file dialogs.
+class SHELL_DIALOGS_EXPORT LinuxShellDialog {
+ public:
+  virtual ~LinuxShellDialog() {}
+
+  // Sets the dynamically loaded singleton that draws the desktop native
+  // UI. This pointer is not owned, and if this method is called a second time,
+  // the first instance is not deleted.
+  static void SetInstance(LinuxShellDialog* instance);
+
+  // Returns a LinuxUI instance for the toolkit used in the user's desktop
+  // environment.
+  //
+  // Can return NULL, in case no toolkit has been set. (For example, if we're
+  // running with the "--ash" flag.)
+  static const LinuxShellDialog* instance();
+
+  // Returns a native file selection dialog.
+  virtual SelectFileDialog* CreateSelectFileDialog(
+      SelectFileDialog::Listener* listener,
+      SelectFilePolicy* policy) const = 0;
+};
+
+}  // namespace ui
+
+#endif  // UI_SHELL_DIALOGS_LINUX_SHELL_DIALOG_H_
+