[DevTools] Rework DevToolsSession interaction with domain handlers.

content/browser/devtools/protocol/dom_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/dom_handler.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/frame_host/render_frame_host_impl.h"
 
 namespace content {
 namespace protocol {
 
-DOMHandler::DOMHandler() : host_(nullptr) {
+DOMHandler::DOMHandler()
+    : DevToolsDomainHandler(DOM::Metainfo::domainName),
+      host_(nullptr) {
 }
 
 DOMHandler::~DOMHandler() {
 }
 
 void DOMHandler::Wire(UberDispatcher* dispatcher) {
   DOM::Dispatcher::wire(dispatcher, this);
 }
 
 void DOMHandler::SetRenderFrameHost(RenderFrameHostImpl* host) {
@@ skipping 18 matching lines @@
           host_->GetProcess()->GetID(),
           base::FilePath(files->get(i)));
 #endif  // OS_WIN
     }
   }
   return Response::FallThrough();
 }
 
 }  // namespace protocol
 }  // namespace content