Add pin icon to the omnibar in windows 8 metro mode.

chrome/browser/ui/metro_pinned_state_observer.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 CHROME_BROWSER_UI_METRO_PINNED_STATE_OBSERVER_H_
+#define CHROME_BROWSER_UI_METRO_PINNED_STATE_OBSERVER_H_
+
+namespace content {
+class WebContents;
+}
+
+// Objects implement this interface to get notified about changes in the
+// metro pinned state.
+class MetroPinnedStateObserver {
+ public:
+  // Notification that the pinned state of the current URL changed.
+  virtual void MetroPinnedStateChanged(content::WebContents* source,
+                                       bool is_pinned) = 0;
+
+ protected:
+  virtual ~MetroPinnedStateObserver() {}
+};
+
+#endif  // CHROME_BROWSER_UI_METRO_PINNED_STATE_OBSERVER_H_