[DevTools] Rework DevToolsSession interaction with domain handlers.

content/browser/devtools/protocol/inspector_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/inspector_handler.h"
 
 #include "content/browser/frame_host/render_frame_host_impl.h"
 
 namespace content {
 namespace protocol {
 
 InspectorHandler::InspectorHandler()
-    : host_(nullptr) {
+    : DevToolsDomainHandler(Inspector::Metainfo::domainName),
+      host_(nullptr) {
 }
 
 InspectorHandler::~InspectorHandler() {
 }
 
 void InspectorHandler::Wire(UberDispatcher* dispatcher) {
   frontend_.reset(new Inspector::Frontend(dispatcher->channel()));
   Inspector::Dispatcher::wire(dispatcher, this);
 }
 
@@ skipping 14 matching lines @@
     frontend_->TargetCrashed();
   return Response::OK();
 }
 
 Response InspectorHandler::Disable() {
   return Response::OK();
 }
 
 }  // namespace protocol
 }  // namespace content