Add a browsing data counter factory on iOS

ios/chrome/browser/browsing_data/ios_browsing_data_counter_factory.h

+// Copyright 2016 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_BROWSING_DATA_IOS_BROWSING_DATA_COUNTER_FACTORY_H_
+#define IOS_CHROME_BROWSER_BROWSING_DATA_IOS_BROWSING_DATA_COUNTER_FACTORY_H_
+
+#include <memory>
+
+#include "base/strings/string_piece.h"
+
+namespace ios {
+class ChromeBrowserState;
+}
+
+namespace browsing_data {
+class BrowsingDataCounter;
+}
+
+class IOSBrowsingDataCounterFactory {
+ public:
+  // Creates a new instance of BrowsingDataCounter that is counting the data
+  // for |browser_state|, related to a given deletion preference |pref_name|.
+  static std::unique_ptr<browsing_data::BrowsingDataCounter>
+  GetForBrowserStateAndPref(ios::ChromeBrowserState* browser_state,
+                            base::StringPiece pref_name);
+
+ private:
+  IOSBrowsingDataCounterFactory();
+  ~IOSBrowsingDataCounterFactory();
+
+  DISALLOW_COPY_AND_ASSIGN(IOSBrowsingDataCounterFactory);
+};
+
+#endif  // IOS_CHROME_BROWSER_BROWSING_DATA_IOS_BROWSING_DATA_COUNTER_FACTORY_H_