[DevTools] Support multiple sessions in content/ domain handlers

content/browser/devtools/protocol/devtools_domain_handler.cc

 // Copyright 2016 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/devtools_domain_handler.h"
 
 #include "content/browser/devtools/devtools_agent_host_impl.h"
 #include "content/browser/devtools/protocol/protocol.h"
 
 namespace content {
 namespace protocol {
 
-// static
-DevToolsSession* DevToolsDomainHandler::GetFirstSession(
-    DevToolsAgentHostImpl* host) {
-  return host->session();
-}
-
 DevToolsDomainHandler::DevToolsDomainHandler(const std::string& name)
     : name_(name) {
 }
 
 DevToolsDomainHandler::~DevToolsDomainHandler() {
 }
 
 void DevToolsDomainHandler::SetRenderFrameHost(RenderFrameHostImpl* host) {
 }
 
 void DevToolsDomainHandler::Wire(UberDispatcher* dispatcher) {
 }
 
 Response DevToolsDomainHandler::Disable() {
   return Response::OK();
 }
 
 }  // namespace protocol
 }  // namespace content