chromeos: Show onscreen bubble when brightness changes.

chrome/browser/chromeos/brightness_bubble.h

Index: chrome/browser/chromeos/brightness_bubble.h
diff --git a/chrome/browser/chromeos/brightness_bubble.h b/chrome/browser/chromeos/brightness_bubble.h
new file mode 100644
index 0000000000000000000000000000000000000000..89553fcf4a364d23054dda4a262824cd1a3a11b4
--- /dev/null
+++ b/chrome/browser/chromeos/brightness_bubble.h
@@ -0,0 +1,32 @@
+// Copyright (c) 2010 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 CHROME_BROWSER_CHROMEOS_BRIGHTNESS_BUBBLE_H_
+#define CHROME_BROWSER_CHROMEOS_BRIGHTNESS_BUBBLE_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "chrome/browser/chromeos/setting_level_bubble.h"
+
+template <typename T> struct DefaultSingletonTraits;
+
+namespace chromeos {
+
+// Singleton class controlling brightness bubble.
+class BrightnessBubble : public SettingLevelBubble {
+ public:
+  static BrightnessBubble* instance();
+
+ private:
+  friend struct DefaultSingletonTraits<BrightnessBubble>;
+
+  BrightnessBubble();
+  virtual ~BrightnessBubble() {}
+
+  DISALLOW_COPY_AND_ASSIGN(BrightnessBubble);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_BRIGHTNESS_BUBBLE_H_