[DevTools] Cleanup DevToolsTarget and DevToolsManagerDelegate after moving to devtools_discovery.

components/devtools_http_handler.gypi

 # Copyright 2015 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.
 
 {
   'targets': [
     {
       'target_name': 'devtools_http_handler',
       'type': 'static_library',
       'dependencies': [
         '../base/base.gyp:base',
+        '../components/components.gyp:devtools_discovery',
         '../content/content.gyp:content_browser',
         '../net/net.gyp:net',
         '../net/net.gyp:http_server',
       ],
       'include_dirs': [
         '..',
       ],
       'sources': [
         'devtools_http_handler/devtools_http_handler.cc',
         'devtools_http_handler/devtools_http_handler.h',
         'devtools_http_handler/devtools_http_handler_delegate.h',
       ],
     },
   ],
 }