Fix a race condition in BrowsingDataRemover.

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 <set>
@@ skipping 435 matching lines @@
   std::unique_ptr<content::PluginDataRemover> plugin_data_remover_;
   base::WaitableEventWatcher watcher_;
 
   // Used to deauthorize content licenses for Pepper Flash.
   std::unique_ptr<PepperFlashSettingsManager> pepper_flash_settings_manager_;
 #endif
 
   uint32_t deauthorize_flash_content_licenses_request_id_ = 0;
   // True if we're waiting for various data to be deleted.
   // These may only be accessed from UI thread in order to avoid races!
+  bool waiting_for_synchronous_clear_operations_ = false;
   bool waiting_for_clear_autofill_origin_urls_ = false;
   bool waiting_for_clear_cache_ = false;
   bool waiting_for_clear_channel_ids_ = false;
   bool waiting_for_clear_flash_content_licenses_ = false;
   // Non-zero if waiting for cookies to be cleared.
   int waiting_for_clear_cookies_count_ = 0;
   bool waiting_for_clear_domain_reliability_monitor_ = false;
   bool waiting_for_clear_form_ = false;
   bool waiting_for_clear_history_ = false;
   bool waiting_for_clear_hostname_resolution_cache_ = false;
@@ skipping 39 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_