[DevTools] Rework DevToolsSession interaction with domain handlers.

content/browser/devtools/protocol/network_handler.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 "content/browser/devtools/protocol/network_handler.h"
 
 #include <stddef.h>
 
 #include "base/containers/hash_tables.h"
 #include "base/strings/stringprintf.h"
@@ skipping 249 matching lines @@
                    base::Unretained(frame_host->GetProcess()
                                         ->GetStoragePartition()
                                         ->GetURLRequestContext()),
                    got_cookies_callback));
   }
 };
 
 }  // namespace
 
 NetworkHandler::NetworkHandler()
-    : host_(nullptr), enabled_(false) {
+    : DevToolsDomainHandler(Network::Metainfo::domainName),
+      host_(nullptr),
+      enabled_(false) {
 }
 
 NetworkHandler::~NetworkHandler() {
 }
 
 void NetworkHandler::Wire(UberDispatcher* dispatcher) {
   Network::Dispatcher::wire(dispatcher, this);
 }
 
 void NetworkHandler::SetRenderFrameHost(RenderFrameHostImpl* host) {
@@ skipping 115 matching lines @@
   *result = false;
   return Response::OK();
 }
 
 std::string NetworkHandler::UserAgentOverride() const {
   return enabled_ ? user_agent_ : std::string();
 }
 
 }  // namespace protocol
 }  // namespace content