DevTools: remove DevToolsTargetDescriptor and its implementations, we are now based on devtools age…

chrome/browser/devtools/chrome_devtools_discovery_provider.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 CHROME_BROWSER_DEVTOOLS_CHROME_DEVTOOLS_DISCOVERY_PROVIDER_H_
 #define CHROME_BROWSER_DEVTOOLS_CHROME_DEVTOOLS_DISCOVERY_PROVIDER_H_
 
 #include "base/macros.h"
 #include "components/devtools_discovery/devtools_discovery_manager.h"
 
 class ChromeDevToolsDiscoveryProvider :
     public devtools_discovery::DevToolsDiscoveryManager::Provider {
  public:
   // Installs provider to devtools_discovery.
   static void Install();
 
   ~ChromeDevToolsDiscoveryProvider() override;
 
   // devtools_discovery::DevToolsDiscoveryManager::Provider implementation.
-  devtools_discovery::DevToolsTargetDescriptor::List GetDescriptors() override;
+  content::DevToolsAgentHost::List GetDescriptors() override;
 
  private:
   ChromeDevToolsDiscoveryProvider();
 
   DISALLOW_COPY_AND_ASSIGN(ChromeDevToolsDiscoveryProvider);
 };
 
 #endif  // CHROME_BROWSER_DEVTOOLS_CHROME_DEVTOOLS_DISCOVERY_PROVIDER_H_