Allow secondary tiles to be unpinned.

chrome/browser/ui/metro_pin_tab_helper.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_PIN_TAB_HELPER_H_
+#define CHROME_BROWSER_UI_METRO_PIN_TAB_HELPER_H_
+
+#include "content/public/browser/web_contents_observer.h"
+
+// Per-tab class to help manage metro pinning.
+class MetroPinTabHelper : public content::WebContentsObserver {
+ public:
+  explicit MetroPinTabHelper(content::WebContents* tab_contents);
+  virtual ~MetroPinTabHelper();
+
+  bool is_pinned() const { return is_pinned_; }
+
+  void TogglePinnedToStartScreen();
+
+  // content::WebContentsObserver overrides:
+  virtual void DidNavigateMainFrame(
+      const content::LoadCommittedDetails& details,
+      const content::FrameNavigateParams& params) OVERRIDE;
+
+ private:
+  // Queries the metro driver about the pinned state of the current URL.
+  void UpdatePinnedStateForCurrentURL();
+
+  // Whether the current URL is pinned to the metro start screen.
+  bool is_pinned_;
+
+  DISALLOW_COPY_AND_ASSIGN(MetroPinTabHelper);
+};
+
+#endif  // CHROME_BROWSER_UI_METRO_PIN_TAB_HELPER_H_