Enabled print server ui flag

- With the flag enabled, users will be able to add their print servers
  through the printer settings page.

Bug: 1015628
Change-Id: Ibb759460dbdea87a3084ba60d388648b7ccfd1a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2025640Reviewed-by: Bailey Berro <baileyberro@chromium.org>
Commit-Queue: jimmy gong <jimmyxgong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738289}

chrome/common/chrome_features.cc

@@ -206,7 +206,7 @@ const base::Feature kPluginVm{"PluginVm", base::FEATURE_DISABLED_BY_DEFAULT};
 
 // Enable adding a print server on Chrome OS.
 const base::Feature kPrintServerUi{"PrintServerUi",
-                                   base::FEATURE_DISABLED_BY_DEFAULT};
+                                   base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Enable chrome://terminal.  Terminal System App will only run on
 // OS_CHROMEOS, but this flag must be defined for all platforms since