[DevTools] Rework DevToolsSession interaction with domain handlers.

content/browser/devtools/browser_devtools_agent_host.h

 // Copyright 2015 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.
 
 #ifndef CONTENT_BROWSER_DEVTOOLS_BROWSER_DEVTOOLS_AGENT_HOST_H_
 #define CONTENT_BROWSER_DEVTOOLS_BROWSER_DEVTOOLS_AGENT_HOST_H_
 
 #include "content/browser/devtools/devtools_agent_host_impl.h"
 
 namespace content {
 
 namespace protocol {
 class IOHandler;
 class MemoryHandler;
 class SystemInfoHandler;
 class TetheringHandler;
 class TracingHandler;
 }  // namespace protocol
 
 class BrowserDevToolsAgentHost : public DevToolsAgentHostImpl {
  private:
   friend class DevToolsAgentHost;
   BrowserDevToolsAgentHost(
       scoped_refptr<base::SingleThreadTaskRunner> tethering_task_runner,
       const CreateServerSocketCallback& socket_callback);
   ~BrowserDevToolsAgentHost() override;
 
   // DevToolsAgentHostImpl implementation.
-  void Attach() override;
-  void Detach() override;
+  void AttachSession(DevToolsSession* session) override;
+  void DetachSession(int session_id) override;
+  bool DispatchProtocolMessage(
+      DevToolsSession* session,
+      const std::string& message) override;
 
   // DevToolsAgentHost implementation.
   std::string GetType() override;
   std::string GetTitle() override;
   GURL GetURL() override;
   bool Activate() override;
   void Reload() override;
   bool Close() override;
-  bool DispatchProtocolMessage(const std::string& message) override;
 
   scoped_refptr<base::SingleThreadTaskRunner> tethering_task_runner_;
   CreateServerSocketCallback socket_callback_;
 
   std::unique_ptr<protocol::IOHandler> io_handler_;
   std::unique_ptr<protocol::MemoryHandler> memory_handler_;
   std::unique_ptr<protocol::SystemInfoHandler> system_info_handler_;
   std::unique_ptr<protocol::TetheringHandler> tethering_handler_;
   std::unique_ptr<protocol::TracingHandler> tracing_handler_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DEVTOOLS_BROWSER_DEVTOOLS_AGENT_HOST_H_