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

chrome/browser/android/devtools_manager_delegate_android.h

Index: chrome/browser/android/devtools_manager_delegate_android.h
diff --git a/chrome/browser/android/devtools_manager_delegate_android.h b/chrome/browser/android/devtools_manager_delegate_android.h
index 4aa8d1778090a0b4970b0fc7354ae5176d49961c..34eba11395f58324374ff6fabab0f4236ad15f3a 100644
--- a/chrome/browser/android/devtools_manager_delegate_android.h
+++ b/chrome/browser/android/devtools_manager_delegate_android.h
@@ -27,8 +27,8 @@ class DevToolsManagerDelegateAndroid :
       content::DevToolsAgentHost* agent_host,
       base::DictionaryValue* command_dict) override;
   std::string GetTargetType(content::RenderFrameHost* host) override;
-  bool DiscoverTargets(
-      const content::DevToolsAgentHost::DiscoveryCallback& callback) override;
+  bool CanDiscoverTargets() override;
+  content::DevToolsAgentHost::List DiscoverTargets() override;
   scoped_refptr<content::DevToolsAgentHost> CreateNewTarget(
       const GURL& url) override;
   std::string GetDiscoveryPageHTML() override;