Refactor sending NOTIFICATION_HISTORY_URL_VISITED

components/history/core/browser/history_backend_observer.h

+// Copyright 2014 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 COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_BACKEND_OBSERVER_H_
+#define COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_BACKEND_OBSERVER_H_
+
+#include "base/macros.h"
+#include "components/history/core/browser/history_types.h"
+
+namespace history {
+
+class HistoryBackend;
+
+class HistoryBackendObserver {
+ public:
+  HistoryBackendObserver() {}
+  virtual ~HistoryBackendObserver() {}
+
+  // Called when user visits an URL.
+  //
+  // The |row| ID will be set to the value that is currently in effect in the
+  // main history database. |redirects| is the list of redirects leading up to
+  // the URL. If we have a redirect chain A -> B -> C and user is visiting C,
+  // then |redirects[0]=B| and |redirects[1]=A|. If there are no redirects,
+  // |redirects| is an empty vector.
+  virtual void OnURLVisited(HistoryBackend* history_backend,
+                            ui::PageTransition transition,
+                            const URLRow& row,
+                            const RedirectList& redirects,
+                            base::Time visit_time) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(HistoryBackendObserver);
+};
+
+}  // namespace history
+
+#endif  // COMPONENTS_HISTORY_CORE_BROWSER_HISTORY_BACKEND_OBSERVER_H_