[Reland] Allow headless TabSocket in isolated worlds & remove obsolete logic

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 e5e29e5f214f3d2c9bf43455efed183a4528d2e8..1e3bc1674432f8901a10e7958ae4f3a42e5ffa3a 100644
--- a/headless/test/headless_browser_test.h
+++ b/headless/test/headless_browser_test.h
@@ -120,8 +120,12 @@ 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();
+  // The TabSocket type to request when creating |web_contents_|.
+  virtual HeadlessWebContents::Builder::TabSocketType GetTabSocketType();
+
+  // Selects between creating the TabSocket only in an isolated world or the
+  // main world.
+  virtual bool GetCreateTabSocketOnlyForIsolatedWorld();
 
  protected:
   void RunTest();