[Mac] Refactor bookmark pulsing into BookmarkBubbleObserverCocoa.

chrome/browser/ui/bookmarks/bookmark_bubble_observer.h

+// 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 CHROME_BROWSER_UI_BOOKMARKS_BOOKMARK_BUBBLE_OBSERVER_H_
+#define CHROME_BROWSER_UI_BOOKMARKS_BOOKMARK_BUBBLE_OBSERVER_H_
+
+namespace bookmarks {
+
+class BookmarkNode;
+
+// Observes the lifetime of a bookmark bubble.
+class BookmarkBubbleObserver {
+ public:
+  virtual ~BookmarkBubbleObserver() {}
+
+  virtual void OnBookmarkBubbleShown(const BookmarkNode* node) = 0;
+  virtual void OnBookmarkBubbleHidden() = 0;
+};
+
+}  // namespace bookmarks
+
+#endif  // CHROME_BROWSER_UI_BOOKMARKS_BOOKMARK_BUBBLE_OBSERVER_H_