Move request_stage.* to extensions/browser/api/declarative_webrequest.

extensions/browser/BUILD.gn

 # 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.
 
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 
 # GYP version: extensions/extensions.gyp:extensions_browser
 source_set("browser") {
   sources = [
@@ skipping 67 matching lines @@
       "api/cast_channel/cast_channel_api.cc",
       "api/cast_channel/cast_channel_api.h",
       "api/cast_channel/cast_message_util.cc",
       "api/cast_channel/cast_message_util.h",
       "api/cast_channel/cast_socket.cc",
       "api/cast_channel/cast_socket.h",
       "api/cast_channel/logger.cc",
       "api/cast_channel/logger.h",
       "api/cast_channel/logger_util.cc",
       "api/cast_channel/logger_util.h",
+      "api/declarative_webrequest/request_stage.cc",
+      "api/declarative_webrequest/request_stage.h",
       "api/declarative_webrequest/webrequest_constants.cc",
       "api/declarative_webrequest/webrequest_constants.h",
       "api/dns/dns_api.cc",
       "api/dns/dns_api.h",
       "api/dns/host_resolver_wrapper.cc",
       "api/dns/host_resolver_wrapper.h",
       "api/execute_code_function.cc",
       "api/execute_code_function.h",
       "api/extensions_api_client.cc",
       "api/extensions_api_client.h",
@@ skipping 304 matching lines @@
       ]
     }
   }
 
   if (is_win) {
     cflags = [
       "/wd4267", # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     ]
   }
 }