[DevTools] Introduce DevToolsSession.

content/browser/devtools/forwarding_agent_host.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/forwarding_agent_host.h"
 
 #include "base/bind.h"
+#include "content/browser/devtools/devtools_session.h"
 #include "content/browser/devtools/protocol/inspector_handler.h"
 
 namespace content {
 
 ForwardingAgentHost::ForwardingAgentHost(
     const std::string& id,
     std::unique_ptr<DevToolsExternalAgentProxyDelegate> delegate)
       : DevToolsAgentHostImpl(id),
         delegate_(std::move(delegate)) {
   NotifyCreated();
 }
 
 ForwardingAgentHost::~ForwardingAgentHost() {
 }
 
 void ForwardingAgentHost::DispatchOnClientHost(const std::string& message) {
-  SendMessageToClient(session_id(), message);
+  SendMessageToClient(session() ? session()->session_id() : 0, message);
 }
 
 void ForwardingAgentHost::ConnectionClosed() {
   HostClosed();
 }
 
 void ForwardingAgentHost::Attach() {
   delegate_->Attach(this);
 }
 
@@ skipping 33 matching lines @@
 
 void ForwardingAgentHost::Reload() {
   delegate_->Reload();
 }
 
 bool ForwardingAgentHost::Close() {
   return delegate_->Close();
 }
 
 }  // content