Allow --enable-experimental-extension-apis in incognito mode when TOUCH_UI is defined.

chrome/browser/chromeos/login/login_utils.cc

Index: chrome/browser/chromeos/login/login_utils.cc
diff --git a/chrome/browser/chromeos/login/login_utils.cc b/chrome/browser/chromeos/login/login_utils.cc
index 72c79a2d76dd7b9b6395e31d9bbd99d51eb8f060..8bf35c89068417cb50c917f57dc8f78c0fbe5c58 100644
--- a/chrome/browser/chromeos/login/login_utils.cc
+++ b/chrome/browser/chromeos/login/login_utils.cc
@@ -432,6 +432,11 @@ std::string LoginUtilsImpl::GetOffTheRecordCommandLine(
 #if defined(HAVE_XINPUT2)
       switches::kTouchDevices,
 #endif
+#if defined(TOUCH_UI)
+      // The virtual keyboard extension for TOUCH_UI (chrome://keyboard) highly
+      // relies on experimental APIs.
+      switches::kEnableExperimentalExtensionApis,
+#endif
   };
   command_line->CopySwitchesFrom(base_command_line,
                                  kForwardSwitches,