1 files changed, 49 insertions, 0 deletions
diff --git a/ios/chrome/browser/tab_parenting_global_observer.h b/ios/chrome/browser/tab_parenting_global_observer.h
new file mode 100644
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+++ b/ios/chrome/browser/tab_parenting_global_observer.h
@@ -0,0 +1,49 @@
+// Copyright 2015 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 IOS_CHROME_BROWSER_TAB_PARENTING_GLOBAL_OBSERVER_H_
+#define IOS_CHROME_BROWSER_TAB_PARENTING_GLOBAL_OBSERVER_H_
+
+#include "base/callback_list.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace base {
+template <typename T>
+struct DefaultSingletonTraits;
+}  // namespace base
+
+namespace web {
+class WebState;
+}
+
+// Allows clients to observe every tab (i.e., WebState) that is parented.
+// NOTE: Should be used only to correspond to //chrome flows that listen for
+// the TAB_PARENTED notification from all sources.
+class TabParentingGlobalObserver {
+ public:
+  typedef base::Callback<void(web::WebState*)> OnTabParentedCallback;
+
+  // Returns the instance of TabParentingGlobalObserver.
+  static TabParentingGlobalObserver* GetInstance();
+
+  // Registers |cb| to be invoked when a tab is parented.
+  scoped_ptr<base::CallbackList<void(web::WebState*)>::Subscription>
+  RegisterCallback(const OnTabParentedCallback& cb);
+
+  // Called to notify all registered callbacks that |web_state| was parented.
+  void OnTabParented(web::WebState* web_state);
+
+ private:
+  friend struct base::DefaultSingletonTraits<TabParentingGlobalObserver>;
+
+  TabParentingGlobalObserver();
+  ~TabParentingGlobalObserver();
+
+  base::CallbackList<void(web::WebState*)> on_tab_parented_callback_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(TabParentingGlobalObserver);
+};
+
+#endif  // IOS_CHROME_BROWSER_TAB_PARENTING_GLOBAL_OBSERVER_H_