Remove the "one at a time" restriction from the browsingData API

chrome/browser/browsing_data/browsing_data_remover.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_BROWSING_DATA_BROWSING_DATA_REMOVER_H_
 #define CHROME_BROWSER_BROWSING_DATA_BROWSING_DATA_REMOVER_H_
 
 #include <stdint.h>
 
 #include <queue>
@@ skipping 287 matching lines @@
 
   // A common reduction of all public Remove[WithFilter][AndReply] methods.
   virtual void RemoveInternal(
       const TimeRange& time_range,
       int remove_mask,
       int origin_type_mask,
       std::unique_ptr<BrowsingDataFilterBuilder> filter_builder,
       Observer* observer);
 
  private:
-  // The clear API needs to be able to toggle removing_ in order to test that
-  // only one BrowsingDataRemover instance can be called at a time.
-  FRIEND_TEST_ALL_PREFIXES(ExtensionBrowsingDataTest, OneAtATime);
   // Testing the private RemovalTask.
   FRIEND_TEST_ALL_PREFIXES(BrowsingDataRemoverTest, MultipleTasks);
 
   // The BrowsingDataRemover tests need to be able to access the implementation
   // of Remove(), as it exposes details that aren't yet available in the public
   // API. As soon as those details are exposed via new methods, this should be
   // removed.
   //
   // TODO(mkwst): See http://crbug.com/113621
   friend class BrowsingDataRemoverTest;
@@ skipping 242 matching lines @@
   // not initialised, so the registry must be mocked out.
   std::unique_ptr<WebappRegistry> webapp_registry_;
 #endif
 
   base::WeakPtrFactory<BrowsingDataRemover> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowsingDataRemover);
 };
 
 #endif  // CHROME_BROWSER_BROWSING_DATA_BROWSING_DATA_REMOVER_H_