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

chrome/browser/devtools/device/devtools_device_discovery.cc

Index: chrome/browser/devtools/device/devtools_device_discovery.cc
diff --git a/chrome/browser/devtools/device/devtools_device_discovery.cc b/chrome/browser/devtools/device/devtools_device_discovery.cc
index 306b25068f3f4f048c755e03718cb343a9a02d1d..fb9901e38d8e67fba4dba33960c8c67740b4023e 100644
--- a/chrome/browser/devtools/device/devtools_device_discovery.cc
+++ b/chrome/browser/devtools/device/devtools_device_discovery.cc
@@ -512,9 +512,9 @@ DevToolsDeviceDiscovery::RemotePage::CreateTarget() {
                                              dict_.get());
   std::string target_path = GetTargetPath(dict_.get());
   std::string type = GetStringProperty(dict_.get(), "type");
-
-  return AgentHostDelegate::GetOrCreateAgentHost(
+  agent_host_ = AgentHostDelegate::GetOrCreateAgentHost(
       device_, browser_id_, local_id, target_path, type, dict_.get());
+  return agent_host_;
 }
 
 // DevToolsDeviceDiscovery::RemoteBrowser -------------------------------------