Automate host start up in browser test

chrome/test/remoting/pin_browsertest.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "chrome/test/remoting/remote_desktop_browsertest.h"
 #include "chrome/test/remoting/waiter.h"
 
 namespace remoting {
@@ skipping 11 matching lines @@
   Cleanup();
 }
 
 IN_PROC_BROWSER_TEST_F(RemoteDesktopBrowserTest, MANUAL_Invalid_PIN) {
   SetUpTestForMe2Me();
 
   content::WebContents* content = app_web_content();
   LoadScript(content, FILE_PATH_LITERAL("invalid_pin_browser_test.js"));
 
   RunJavaScriptTest(content, "Invalid_PIN", "{"
-    "pin: '" + me2me_pin() + "'"
+    // Append arbitrary characters after the pin to make it invalid.
+    "pin: '" + me2me_pin() + "ABC'"
   "}");
 
   Cleanup();
 }
 
 IN_PROC_BROWSER_TEST_F(RemoteDesktopBrowserTest, MANUAL_Update_PIN) {
   SetUpTestForMe2Me();
 
   content::WebContents* content = app_web_content();
   LoadScript(content, FILE_PATH_LITERAL("update_pin_browser_test.js"));
 
   RunJavaScriptTest(content, "Update_PIN", "{"
     "old_pin: '" + me2me_pin() + "',"
     "new_pin: '314159'"
   "}");
 
   Cleanup();
 }
 
 }  // namespace remoting