linux_aura: Three fixes for switching themes.

ui/linux_ui/linux_ui.h

 // Copyright (c) 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_LINUX_UI_LINUX_UI_H_
 #define UI_LINUX_UI_LINUX_UI_H_
 
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/linux_ui/linux_ui_export.h"
 #include "ui/shell_dialogs/linux_shell_dialog.h"
@@ skipping 29 matching lines @@
   // environment.
   //
   // Can return NULL, in case no toolkit has been set. (For example, if we're
   // running with the "--ash" flag.)
   static const LinuxUI* instance();
 
   // Returns an themed image per theme_provider.h
   virtual bool UseNativeTheme() const = 0;
   virtual gfx::Image GetThemeImageNamed(int id) const = 0;
   virtual bool GetColor(int id, SkColor* color) const = 0;
+  virtual bool HasCustomImage(int id) const = 0;
 
   // Returns a NativeTheme that will provide system colors and draw system
   // style widgets.
   virtual NativeTheme* GetNativeTheme() const = 0;
+
+  // Returns whether we should be using the native theme provided by this
+  // object by default.
+  virtual bool GetDefaultUsesSystemTheme() const = 0;
 };
 
 }  // namespace ui
 
 #endif  // UI_LINUX_UI_LINUX_UI_H_