ChromeOS should have UTC timezone option.

chrome/app/chromeos_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- ChromeOS-specific strings (included from generated_resources.grd).
      Everything in this file is wrapped in <if expr="chromeos">. -->
 <grit-part>
   <message name="IDS_EMPTY_STRING" desc="Empty string, exist only to make code generic. No translation required.">
   </message>
   <!-- Idle logout dialog for retail mode -->
   <message name="IDS_IDLE_LOGOUT_TITLE" desc="Dialog title for the idle logout dialog. Used in retail mode only.">
     Are you still there?
   </message>
@@ skipping 2100 matching lines @@
   </message>
   <message name="IDS_OPTIONS_SETTINGS_TIMEZONE_DESCRIPTION" desc="In the settings tab, the text next to the timezone combobox.">
     Time zone:
   </message>
   <message name="IDS_OPTIONS_SETTINGS_USE_24HOUR_CLOCK_DESCRIPTION" desc="In the settings tab, the text next to the checkbox that enables 24-hour clock.">
     Use 24-hour clock
   </message>
   <message name="IDS_OPTIONS_SETTINGS_TIMEZONE_DISPLAY_TEMPLATE" desc="In the settings tab, the display template of a timezone in the pull-down list of timezones">
     (<ph name="UTCOffset">$1<ex>UTC-8:00</ex></ph>) <ph name="LongTZName">$2<ex>Pacific Standard Time</ex></ph> (<ph name="ExemplarCity">$3<ex>Los Angeles</ex></ph>)
   </message>
+  <message name="IDS_OPTIONS_SETTINGS_TIMEZONE_DISPLAY_NAME_UTC" desc="This is the display name of UTC/GMT timezone for timezone option in user settings.">
+    Coordinated Universal Time (UTC/GMT)
+  </message>
   <message name="IDS_OPTIONS_SETTINGS_BRIGHTNESS_DESCRIPTION" desc="In the settings tab, the text next to the buttons for screen brightness.">
     Brightness:
   </message>
   <message name="IDS_OPTIONS_SETTINGS_BRIGHTNESS_DECREASE" desc="In the settings tab, the text of the button to decrease the screen brightness.">
     Decrease
   </message>
   <message name="IDS_OPTIONS_SETTINGS_BRIGHTNESS_INCREASE" desc="In the settings tab, the text of the button to increase the screen brightness.">
     Increase
   </message>
   <message name="IDS_OPTIONS_SETTINGS_TAP_TO_CLICK_ENABLED_DESCRIPTION" desc="In the settings tab, the text next to the checkbox that enables tap-to-click.">
@@ skipping 4262 matching lines @@
     Installing
   </message>
   <message name="IDS_FLAGS_PRINTER_PROVIDER_SEARCH_APP_NAME" desc="Name of the flag used to enable launching Chrome Web Store Gallery widget app for searching for printer provider apps.">
     Chrome Web Store Gallery app for printer drivers
   </message>
   <message name="IDS_FLAGS_PRINTER_PROVIDER_SEARCH_APP_DESCRIPTION" desc="Description of a flag in chrome://flags that enables launching Chrome Web Store Gallery widget app for searching for printer provider apps.">
     Enables Chrome Web Store Gallery app for printer drivers. The app searches Chrome Web Store for extensions that support printing to a USB printer with specific USB ID.
   </message>
 
 </grit-part>