Add display scaling and rotation shortcuts to keyboard overlay.

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 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>
   <message name="IDS_IDLE_LOGOUT_WARNING_RESTART" desc="Restart label for the idle logout dialog. Used in retail mode only..">
     This computer will reset in <ph name="LOGOUT_TIME_LEFT">$1<ex>20</ex></ph> seconds.
@@ skipping 2966 matching lines @@
   </message>
   <message name="IDS_KEYBOARD_OVERLAY_REOPEN_LAST_CLOSED_TAB" desc="The text in the keyboard overlay to explain the shortcut.">
     Reopen last-closed tab
   </message>
   <message name="IDS_KEYBOARD_OVERLAY_REPORT_ISSUE" desc="The text in the keyboard overlay to explain the shortcut (report an issue).">
     Report issue
   </message>
   <message name="IDS_KEYBOARD_OVERLAY_RESET_ZOOM" desc="The text in the keyboard overlay to explain the shortcut.">
     Reset zoom
   </message>
+  <message name="IDS_KEYBOARD_OVERLAY_ROTATE_SCREEN" desc="The text in the keyboard overlay to explain the shortcut (Rotate the screen).">
+    Rotate screen
+  </message>
   <message name="IDS_KEYBOARD_OVERLAY_SAVE" desc="The text in the keyboard overlay to explain the shortcut (save page as a file).">
     Save
   </message>
+  <message name="IDS_KEYBOARD_OVERLAY_SCALE_DOWN_UI" desc="The text in the keyboard overlay to explain the shortcut (Scale down the UI).">
+    Scale down UI
+  </message>
+  <message name="IDS_KEYBOARD_OVERLAY_SCALE_UP_UI" desc="The text in the keyboard overlay to explain the shortcut (Scale up the UI).">
+    Scale up UI
+  </message>
   <message name="IDS_KEYBOARD_OVERLAY_SCREENSHOT_REGION" desc="The text in the keyboard overlay to explain the shortcut (take a screenshot of the selected region).">
     Screenshot region
   </message>
   <message name="IDS_KEYBOARD_OVERLAY_SCROLL_UP_ONE_PAGE" desc="The text in the keyboard overlay to explain the shortcut.">
     Scroll up one page
   </message>
   <message name="IDS_KEYBOARD_OVERLAY_SELECT_ALL" desc="The text in the keyboard overlay to explain the shortcut.">
     Select all
   </message>
   <message name="IDS_KEYBOARD_OVERLAY_SELECT_PREVIOUS_INPUT_METHOD" desc="The text in the keyboard overlay to explain the shortcut.">
@@ skipping 564 matching lines @@
   <message name="IDS_KIOSK_APP_ERROR_UNABLE_TO_MOUNT" desc="Error message used when a kiosk app fails to launch due to cryptohome error.">
     Kryptonite! The cryptohome for the kiosk application could not be mounted.
   </message>
   <message name="IDS_KIOSK_APP_ERROR_UNABLE_TO_INSTALL" desc="Error message used when a kiosk app fails to launch due to install failure.">
     Kiosk application could not be installed.
   </message>
   <message name="IDS_KIOSK_APP_ERROR_USER_CANCEL" desc="Error message used when a kiosk app launch is canceled by user.">
     Kiosk application launch canceled.
   </message>
 </grit-part>