Add support for uninstalling components and use it in SupervisedUserWhitelistInstaller.

chrome/browser/net/crl_set_fetcher.cc

 // 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.
 
 #include "chrome/browser/net/crl_set_fetcher.h"
 
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/rand_util.h"
@@ skipping 223 matching lines @@
   }
 
   return true;
 }
 
 bool CRLSetFetcher::GetInstalledFile(
     const std::string& file, base::FilePath* installed_file) {
   return false;
 }
 
+bool CRLSetFetcher::Uninstall() {
+  return false;
+}
+
 CRLSetFetcher::~CRLSetFetcher() {}