[DevTools] Cleanup DevToolsTarget and DevToolsManagerDelegate after moving to devtools_discovery.

chrome/browser/devtools/chrome_devtools_manager_delegate.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_DEVTOOLS_CHROME_DEVTOOLS_MANAGER_DELEGATE_H_
 #define CHROME_BROWSER_DEVTOOLS_CHROME_DEVTOOLS_MANAGER_DELEGATE_H_
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/devtools/devtools_network_protocol_handler.h"
 #include "content/public/browser/devtools_manager_delegate.h"
 
 class ChromeDevToolsManagerDelegate : public content::DevToolsManagerDelegate {
  public:
   ChromeDevToolsManagerDelegate();
   ~ChromeDevToolsManagerDelegate() override;
 
   // content::DevToolsManagerDelegate implementation.
   void Inspect(content::BrowserContext* browser_context,
                content::DevToolsAgentHost* agent_host) override;
   void DevToolsAgentStateChanged(content::DevToolsAgentHost* agent_host,
                                  bool attached) override;
   base::DictionaryValue* HandleCommand(
       content::DevToolsAgentHost* agent_host,
       base::DictionaryValue* command_dict) override;
-  scoped_ptr<content::DevToolsTarget> CreateNewTarget(const GURL& url) override;
-  void EnumerateTargets(TargetCallback callback) override;
-  std::string GetPageThumbnailData(const GURL& url) override;
 
  private:
   scoped_ptr<DevToolsNetworkProtocolHandler> network_protocol_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeDevToolsManagerDelegate);
 };
 
 #endif  // CHROME_BROWSER_DEVTOOLS_CHROME_DEVTOOLS_MANAGER_DELEGATE_H_