[DevTools] Migrate from AgentStateCallbacks to DevToolsAgentHostObserver.

chrome/browser/android/devtools_manager_delegate_android.h

 // 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.
 
 #ifndef CHROME_BROWSER_ANDROID_DEVTOOLS_MANAGER_DELEGATE_ANDROID_H_
 #define CHROME_BROWSER_ANDROID_DEVTOOLS_MANAGER_DELEGATE_ANDROID_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
+#include "content/public/browser/devtools_agent_host_observer.h"
 #include "content/public/browser/devtools_manager_delegate.h"
 
 class DevToolsNetworkProtocolHandler;
 
-class DevToolsManagerDelegateAndroid : public content::DevToolsManagerDelegate {
+class DevToolsManagerDelegateAndroid :
+    public content::DevToolsManagerDelegate,
+    public content::DevToolsAgentHostObserver {
  public:
   DevToolsManagerDelegateAndroid();
   ~DevToolsManagerDelegateAndroid() override;
 
+ private:
   // content::DevToolsManagerDelegate implementation.
-  void DevToolsAgentStateChanged(content::DevToolsAgentHost* agent_host,
-                                 bool attached) override;
   base::DictionaryValue* HandleCommand(
       content::DevToolsAgentHost* agent_host,
       base::DictionaryValue* command_dict) override;
   std::string GetTargetType(content::RenderFrameHost* host) override;
   std::string GetTargetTitle(content::RenderFrameHost* host) override;
   bool DiscoverTargets(
       const content::DevToolsAgentHost::DiscoveryCallback& callback) override;
   scoped_refptr<content::DevToolsAgentHost> CreateNewTarget(
       const GURL& url) override;
   std::string GetDiscoveryPageHTML() override;
 
- private:
+  // content::DevToolsAgentHostObserver overrides.
+  void DevToolsAgentHostAttached(
+      content::DevToolsAgentHost* agent_host) override;
+  void DevToolsAgentHostDetached(
+      content::DevToolsAgentHost* agent_host) override;
+
   std::unique_ptr<DevToolsNetworkProtocolHandler> network_protocol_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(DevToolsManagerDelegateAndroid);
 };
 
 #endif  // CHROME_BROWSER_ANDROID_DEVTOOLS_MANAGER_DELEGATE_ANDROID_H_