Make --top-chrome-touch-ui permanent

This flag is really useful for debugging and used by UX and QA as part
of testing.

Bug: None
Change-Id: Ia11e76df8bc06321d58e1721c8f10ca4d16e643f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2008431
Commit-Queue: Peter Boström <pbos@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#733800}

chrome/browser/flag-metadata.json

@@ -3471,8 +3471,12 @@
   },
   {
     "name": "top-chrome-touch-ui",
-    "owners": [ "chrome-desktop-ui-sea@google.com" ],
-    "expiry_milestone": 81
+    "owners": [ "pbos", "chrome-desktop-ui-sea@google.com" ],
+    // This flag is used to easily swap into touch-mode for UI development where
+    // the UI differs significantly between touch/non-touch modes. This is
+    // exposed in chrome://flags to allow QA and UXers to verify touch-related
+    // behavior without access to touch devices.
+    "expiry_milestone": -1
   },
   {
     "name": "touch-events",

chrome/browser/flag-never-expire-list.json

@@ -81,6 +81,7 @@
   "show-taps",
   "show-touch-hud",
   "tint-gl-composited-content",
+  "top-chrome-touch-ui",
   "translate-android-manual-trigger",
   "ui-disable-partial-swap",
   "ui-slow-animations",