Convert WaitableEvent::EventCallback to OnceCallback

chrome/browser/browsing_data/chrome_browsing_data_remover_delegate.cc

 // 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.
 
 #include "chrome/browser/browsing_data/chrome_browsing_data_remover_delegate.h"
 
 #include <set>
 #include <string>
 #include <utility>
 
@@ skipping 896 matching lines @@
     if (filter_builder.IsEmptyBlacklist()) {
       DCHECK(!plugin_data_remover_);
       plugin_data_remover_.reset(
           content::PluginDataRemover::Create(profile_));
       base::WaitableEvent* event =
           plugin_data_remover_->StartRemoving(delete_begin_);
 
       base::WaitableEventWatcher::EventCallback watcher_callback = base::Bind(
           &ChromeBrowsingDataRemoverDelegate::OnWaitableEventSignaled,
           weak_ptr_factory_.GetWeakPtr());
-      watcher_.StartWatching(event, watcher_callback);
+      watcher_.StartWatching(event, std::move(watcher_callback));
     } else {
       // TODO(msramek): Store filters from the currently executed task on the
       // object to avoid having to copy them to callback methods.
       flash_lso_helper_->StartFetching(base::Bind(
           &ChromeBrowsingDataRemoverDelegate::OnSitesWithFlashDataFetched,
           weak_ptr_factory_.GetWeakPtr(),
           filter_builder.BuildPluginFilter()));
     }
   }
 #endif
@@ skipping 206 matching lines @@
 }
 
 void ChromeBrowsingDataRemoverDelegate::
 OnDeauthorizeFlashContentLicensesCompleted(
     uint32_t request_id,
     bool /* success */) {
   DCHECK_EQ(request_id, deauthorize_flash_content_licenses_request_id_);
   clear_flash_content_licenses_.GetCompletionCallback().Run();
 }
 #endif