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

content/public/browser/devtools_manager_delegate.h

Index: content/public/browser/devtools_manager_delegate.h
diff --git a/content/public/browser/devtools_manager_delegate.h b/content/public/browser/devtools_manager_delegate.h
index 19c0dbefbb5c568e29a634a0f2a8746ea5f01734..170009212d5772a3d5495f15e5d61eaab85d9f2a 100644
--- a/content/public/browser/devtools_manager_delegate.h
+++ b/content/public/browser/devtools_manager_delegate.h
@@ -35,11 +35,14 @@ class CONTENT_EXPORT DevToolsManagerDelegate {
   // 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);
@@ -51,11 +54,9 @@ class CONTENT_EXPORT DevToolsManagerDelegate {
 
   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();