Add HeadlessTabSocket

headless/test/headless_browser_test.h

Index: headless/test/headless_browser_test.h
diff --git a/headless/test/headless_browser_test.h b/headless/test/headless_browser_test.h
index f2d0cca3f63110ef7ca60babe8f6e07857e834cc..78a2f97142d68b5e6cb85c7964e62b1e8fe439fa 100644
--- a/headless/test/headless_browser_test.h
+++ b/headless/test/headless_browser_test.h
@@ -121,6 +121,9 @@ class HeadlessAsyncDevTooledBrowserTest : public HeadlessBrowserTest,
   // the map returned is empty.
   virtual ProtocolHandlerMap GetProtocolHandlers();
 
+  // Whether or not we should request a TabSocket when creating |web_contents_|.
+  virtual bool GetCreateTabSocket();
+
  protected:
   void RunTest();