[DevTools] Migrate from AgentStateCallbacks to DevToolsAgentHostObserver.

content/browser/devtools/devtools_agent_host_impl.h

 // Copyright (c) 2012 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_DEVTOOLS_AGENT_HOST_IMPL_H_
 #define CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_AGENT_HOST_IMPL_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 55 matching lines @@
 
   virtual bool DispatchProtocolMessage(const std::string& message) = 0;
   virtual void InspectElement(int x, int y);
 
   void HostClosed();
   void SendMessageToClient(int session_id, const std::string& message);
   devtools::DevToolsIOContext* GetIOContext() { return &io_context_; }
 
   int session_id() { DCHECK(client_); return session_id_; }
 
-  static void NotifyCallbacks(DevToolsAgentHostImpl* agent_host, bool attached);
-
  private:
   friend class DevToolsAgentHost; // for static methods
   bool InnerAttach(DevToolsAgentHostClient* client, bool force);
   void InnerDetach();
+  void NotifyAttached();
+  void NotifyDetached();
 
   const std::string id_;
   int session_id_;
   DevToolsAgentHostClient* client_;
   devtools::DevToolsIOContext io_context_;
+  static int s_attached_count_;
 };
 
 class DevToolsMessageChunkProcessor {
  public:
   using SendMessageCallback = base::Callback<void(int, const std::string&)>;
   explicit DevToolsMessageChunkProcessor(const SendMessageCallback& callback);
   ~DevToolsMessageChunkProcessor();
 
   std::string state_cookie() const { return state_cookie_; }
   void set_state_cookie(const std::string& cookie) { state_cookie_ = cookie; }
   int last_call_id() const { return last_call_id_; }
   bool ProcessChunkedMessageFromAgent(const DevToolsMessageChunk& chunk);
 
  private:
   SendMessageCallback callback_;
   std::string message_buffer_;
   uint32_t message_buffer_size_;
   std::string state_cookie_;
   int last_call_id_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_AGENT_HOST_IMPL_H_