Override CreateNewTarget in the HeadlessDevToolsManagerDelegate to be able to create new tabs in he…

headless/lib/browser/headless_devtools_manager_delegate.h

Index: headless/lib/browser/headless_devtools_manager_delegate.h
diff --git a/headless/lib/browser/headless_devtools_manager_delegate.h b/headless/lib/browser/headless_devtools_manager_delegate.h
index c891e8246c6cde5d7b45b26e27cd60e27d502015..29c8c1d870d3b6235e64edac47a711f7dc0c7156 100644
--- a/headless/lib/browser/headless_devtools_manager_delegate.h
+++ b/headless/lib/browser/headless_devtools_manager_delegate.h
@@ -27,6 +27,8 @@ class HeadlessDevToolsManagerDelegate
   // DevToolsManagerDelegate implementation:
   base::DictionaryValue* HandleCommand(content::DevToolsAgentHost* agent_host,
                                        base::DictionaryValue* command) override;
+  scoped_refptr<content::DevToolsAgentHost> CreateNewTarget(
+      const GURL& url) override;
   std::string GetDiscoveryPageHTML() override;
   std::string GetFrontendResource(const std::string& path) override;