[Devtools] Allow User-Agent header override for Websockets

content/public/browser/devtools_agent_host.h

Index: content/public/browser/devtools_agent_host.h
diff --git a/content/public/browser/devtools_agent_host.h b/content/public/browser/devtools_agent_host.h
index 62b5a6e7ae29aad7c84388153f1ea05c222d13b4..09422847590bfe645d9b597fb5ff407abf889897 100644
--- a/content/public/browser/devtools_agent_host.h
+++ b/content/public/browser/devtools_agent_host.h
@@ -157,6 +157,9 @@ class CONTENT_EXPORT DevToolsAgentHost
   // Terminates all debugging sessions and detaches all clients.
   static void DetachAllClients();
 
+  // Gets the user agent override currently set for the frame.
+  virtual std::string GetUserAgentOverride() = 0;
+
   typedef base::Callback<void(DevToolsAgentHost*, bool attached)>
       AgentStateCallback;