MD Settings: Display: Add unified desktop control and modify api

chrome/app/settings_strings.grdp

Index: chrome/app/settings_strings.grdp
diff --git a/chrome/app/settings_strings.grdp b/chrome/app/settings_strings.grdp
index 6a9d45e350a03a8d78a292af048396126f3c674a..feb94c4a1eb55d32d4fc99f4c75bad10767f08cf 100644
--- a/chrome/app/settings_strings.grdp
+++ b/chrome/app/settings_strings.grdp
@@ -2828,6 +2828,9 @@
     <message name="IDS_SETTINGS_DISPLAY_MIRROR" desc="In Device Settings > Displays, the label for the control for mirroring.">
       Mirroring
     </message>
+    <message name="IDS_SETTINGS_DISPLAY_UNIFIED_DESKTOP" desc="In Device Settings > Displays, the label for the control for the unified desktop feature.">
+      Allow windows to span displays
+    </message>
     <message name="IDS_SETTINGS_DISPLAY_SCREEN" desc="In Device Settings > Displays, the label for the dropdown menu for changing the dispay type.">
       Screen
     </message>
@@ -2876,12 +2879,6 @@
     <message name="IDS_SETTINGS_DISPLAY_OVERSCAN_RESET" desc="Label for resetting overscan calibration.">
       Reset
     </message>
-    <message name="IDS_SETTINGS_DISPLAY_MIRRORING_ON" desc="Label indicating that the displays are currently mirrored">
-      On
-    </message>
-    <message name="IDS_SETTINGS_DISPLAY_MIRRORING_OFF" desc="Label indicating that the displays are currently not mirrored">
-      Off
-    </message>
     <message name="IDS_SETTINGS_DISPLAY_TOUCH_CALIBRATION_TITLE" desc="In Device Settings > Displays, the label for initiating touch calibration.">
       Calibrate touchscreen
     </message>