Remove dead code

chrome/browser/extensions/api/history/history_api.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_EXTENSIONS_API_HISTORY_HISTORY_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_HISTORY_HISTORY_API_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 96 matching lines @@
   // ExtensionFunction:
   virtual bool RunAsync() OVERRIDE;
 
   // Return true if the async call was completed, false otherwise.
   virtual bool RunAsyncImpl() = 0;
 
   // Call this method to report the results of the async method to the caller.
   // This method calls Release().
   virtual void SendAsyncResponse();
 
-  // The consumer for the HistoryService callbacks.
-  CancelableRequestConsumer cancelable_consumer_;
+  // The task tracker for the HistoryService callbacks.
   base::CancelableTaskTracker task_tracker_;
 
  private:
   // The actual call to SendResponse.  This is required since the semantics for
   // CancelableRequestConsumerT require it to be accessed after the call.
   void SendResponseToCallback();
 };
 
 class HistoryGetVisitsFunction : public HistoryFunctionWithCallback {
  public:
@@ skipping 72 matching lines @@
   // HistoryFunctionWithCallback:
   virtual bool RunAsyncImpl() OVERRIDE;
 
   // Callback for the history service to acknowledge deletion.
   void DeleteComplete();
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_HISTORY_HISTORY_API_H_