Add power-user keyboard mode for ChromeOS with Search key acting as a typical Fn key.

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="pp_ifdef('chromeos')">. -->
 <grit-part>
   <!-- Idle Logout Dialog Strings -->
   <message name="IDS_IDLE_LOGOUT_TITLE" desc="Dialog title for the idle logout dialog">
     Are you still there?
   </message>
   <message name="IDS_IDLE_LOGOUT_WARNING_RESTART" desc="Restart label for the idle logout dialog">
     This computer will reset in <ph name="LOGOUT_TIME_LEFT">$1<ex>20</ex></ph> seconds.
@@ skipping 2051 matching lines @@
     Alt
   </message>
   <message name="IDS_OPTIONS_SETTINGS_LANGUAGES_KEY_VOID"
            desc="The dropdown list item for 'Customize modifier keys' overlay">
     Disabled
   </message>
   <message name="IDS_OPTIONS_SETTINGS_LANGUAGES_KEY_CAPS_LOCK"
            desc="The dropdown list item for 'Customize modifier keys' overlay">
     Caps Lock
   </message>
+  <message name="IDS_OPTIONS_SETTINGS_LANGUAGES_KEY_SEARCH_AS_FUNCTION"
+           desc="The checkbox to enable the Search key to act as a Function key">
+    Use the Search key to access extended keybindings.
+  </message>
   <message name="IDS_OPTIONS_NO_POINTING_DEVICES" desc="Text shown when there is neither a touchpad nor a mouse.">
     No mouse or touchpad was detected.
   </message>
   <message name="IDS_OPTIONS_POINTER_MOUSE_OVERLAY_TITLE" desc="The title for 'Pointer settings' overlay for Mouse only.">
     Mouse settings
   </message>
   <message name="IDS_OPTIONS_POINTER_TOUCHPAD_OVERLAY_TITLE" desc="The title for 'Pointer settings' overlay for Touchpad only.">
     Touchpad settings
   </message>
   <message name="IDS_OPTIONS_POINTER_TOUCHPAD_MOUSE_OVERLAY_TITLE" desc="The title for 'Pointer settings' overlay for Touchpad and Mouse.">
@@ skipping 1386 matching lines @@
   <message name="IDS_LOGIN_MANAGED_BY_STATUS_NETWORK_ERROR" desc="Text for the network error status in 'Managed by DOMAIN' label on login screen.">
     Network error while communicating with the device management service.
   </message>
   <message name="IDS_LOGIN_MANAGED_BY_NOTICE" desc="Text for the notification bar on the login screen showing that this is a managed device.">
     This device is managed by <ph name="DOMAIN">$1<ex>yourdomain.com</ex></ph>.
   </message>
   <message name="IDS_LOGIN_MANAGED_REPORTING_HINT" desc="Text for the hint on reporting features displayed in the enterprise notification bar on the login screen.">
     Device usage may be tracked.
   </message>
 </grit-part>