[Extensions] Short-circuit activity logging if not enabled

extensions/shell/browser/shell_extensions_browser_client.cc

 // Copyright 2014 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/shell/browser/shell_extensions_browser_client.h"
 
 #include <utility>
 
 #include "base/memory/ptr_util.h"
 #include "build/build_config.h"
@@ skipping 149 matching lines @@
 }
 
 bool ShellExtensionsBrowserClient::IsRunningInForcedAppMode() {
   return false;
 }
 
 bool ShellExtensionsBrowserClient::IsLoggedInAsPublicAccount() {
   return false;
 }
 
-ApiActivityMonitor* ShellExtensionsBrowserClient::GetApiActivityMonitor(
-    BrowserContext* context) {
-  // app_shell doesn't monitor API function calls or events.
-  return NULL;
-}
-
 ExtensionSystemProvider*
 ShellExtensionsBrowserClient::GetExtensionSystemFactory() {
   return ShellExtensionSystemFactory::GetInstance();
 }
 
 void ShellExtensionsBrowserClient::RegisterExtensionFunctions(
     ExtensionFunctionRegistry* registry) const {
   // Register core extension-system APIs.
   api::GeneratedFunctionRegistry::RegisterAll(registry);
 
@@ skipping 58 matching lines @@
   api_client_.reset(api_client);
 }
 
 ExtensionWebContentsObserver*
 ShellExtensionsBrowserClient::GetExtensionWebContentsObserver(
     content::WebContents* web_contents) {
   return ShellExtensionWebContentsObserver::FromWebContents(web_contents);
 }
 
 }  // namespace extensions