Remove dead extensions tracking code.

extensions/browser/api/web_request/web_request_api.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 "extensions/browser/api/web_request/web_request_api.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 2130 matching lines @@
   bool success =
       ExtensionWebRequestEventRouter::GetInstance()->AddEventListener(
           profile_id(), extension_id_safe(), extension_name,
           GetEventHistogramValue(event_name), event_name, sub_event_name,
           filter, extra_info_spec, embedder_process_id, web_view_instance_id,
           ipc_sender_weak());
   EXTENSION_FUNCTION_VALIDATE(success);
 
   helpers::ClearCacheOnNavigation();
 
-  if (!extension_id_safe().empty()) {
-    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
-                            base::Bind(&helpers::NotifyWebRequestAPIUsed,
-                                       profile_id(), extension_id_safe()));
-  }
-
   return RespondNow(NoArguments());
 }
 
 void WebRequestInternalEventHandledFunction::OnError(
     const std::string& event_name,
     const std::string& sub_event_name,
     uint64_t request_id,
     std::unique_ptr<ExtensionWebRequestEventRouter::EventResponse> response) {
   ExtensionWebRequestEventRouter::GetInstance()->OnEventHandled(
       profile_id(),
@@ skipping 193 matching lines @@
   // Since EventListeners are segmented by browser_context, check that
   // last, as it is exceedingly unlikely to be different.
   return extension_id == that.extension_id &&
          sub_event_name == that.sub_event_name &&
          web_view_instance_id == that.web_view_instance_id &&
          embedder_process_id == that.embedder_process_id &&
          browser_context == that.browser_context;
 }
 
 }  // namespace extensions