DevTools: retain DTAH in all the targets to match their life time.

content/public/browser/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 CONTENT_PUBLIC_BROWSER_DEVTOOLS_MANAGER_DELEGATE_H_
 #define CONTENT_PUBLIC_BROWSER_DEVTOOLS_MANAGER_DELEGATE_H_
 
 #include <memory>
 #include <string>
 
@@ skipping 17 matching lines @@
 
   // Returns DevToolsAgentHost type to use for given |host| target.
   virtual std::string GetTargetType(RenderFrameHost* host);
 
   // Returns DevToolsAgentHost title to use for given |host| target.
   virtual std::string GetTargetTitle(RenderFrameHost* host);
 
   // Returns DevToolsAgentHost title to use for given |host| target.
   virtual std::string GetTargetDescription(RenderFrameHost* host);
 
+  // Returns whether embedder wants to be responsible for targets.

[dgozman, 2017/04/22 00:00:45]

nit: extra dot at the end..

+  // discovery. If yes, DiscoverTargets is called.
+  virtual bool CanDiscoverTargets();
+
   // Returns all targets embedder would like to report as discoverable.
   // If returns false, all targets content is aware of and only those
   // should be discoverable.
-  virtual bool DiscoverTargets(
-      const DevToolsAgentHost::DiscoveryCallback& callback);
+  virtual DevToolsAgentHost::List DiscoverTargets();
 
   // Creates new inspectable target given the |url|.
   virtual scoped_refptr<DevToolsAgentHost> CreateNewTarget(const GURL& url);
 
   // Result ownership is passed to the caller.
   virtual base::DictionaryValue* HandleCommand(
       DevToolsAgentHost* agent_host,
       base::DictionaryValue* command);
 
   using CommandCallback =
       base::Callback<void(std::unique_ptr<base::DictionaryValue> response)>;
-  // Handle async command, feed response to CommandCallback when it is ready.
   virtual bool HandleAsyncCommand(DevToolsAgentHost* agent_host,
                                   base::DictionaryValue* command,
                                   const CommandCallback& callback);
-
   // Should return discovery page HTML that should list available tabs
   // and provide attach links.
   virtual std::string GetDiscoveryPageHTML();
 
   // Returns frontend resource data by |path|.
   virtual std::string GetFrontendResource(const std::string& path);
 
   virtual ~DevToolsManagerDelegate();
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_DEVTOOLS_MANAGER_DELEGATE_H_