chromeos: Add Power device page to chrome://md-settings.

chrome/app/settings_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Settings-specific strings (included from generated_resources.grd). -->
 <grit-part>
   <!-- About Page -->
   <message name="IDS_SETTINGS_ABOUT_PAGE_BROWSER_VERSION" desc="The text label describing the version of the browser, example: Version 57.0.2937.0 (Developer Build) unknown (64-bit)">
     Version <ph name="PRODUCT_VERSION">$1<ex>15.0.865.0</ex></ph> (<ph name="PRODUCT_CHANNEL">$2<ex>Developer Build</ex></ph>) <ph name="PRODUCT_MODIFIER">$3</ph> <ph name="PRODUCT_VERSION_BITS">$4</ph>
   </message>
   <if expr="chromeos">
     <message name="IDS_SETTINGS_ABOUT_PAGE_DETAILED_BUILD_INFO" desc="Label describing the section that shows detailed information about the current Chrome build.">
       Detailed build information
@@ skipping 2671 matching lines @@
     <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
     </message>
     <message name="IDS_SETTINGS_DISPLAY_TOUCH_CALIBRATION_TEXT" desc="In Device Settings > Displays, the sublabel for initiating touch calibration.">
       Define the boundaries of your touchscreen over the display
     </message>
 
+    <!-- Power -->
+    <message name="IDS_SETTINGS_POWER_TITLE" desc="In Device Settings, the title for power management.">
+      Power
+    </message>
+
     <!-- Storage -->
     <message name="IDS_SETTINGS_STORAGE_TITLE" desc="In Device Settings, the title for storage management.">
       Storage management
     </message>
     <message name="IDS_SETTINGS_STORAGE_ITEM_IN_USE" desc="In Device Settings > Storage, label for the used storage size of Chrome OS internal storage.">
       In use
     </message>
     <message name="IDS_SETTINGS_STORAGE_ITEM_AVAILABLE" desc="In Device Settings > Storage, label for the available storage size of Chrome OS internal storage.">
       Available
     </message>
@@ skipping 53 matching lines @@
       System
     </message>
     <message name="IDS_SETTINGS_SYSTEM_HARDWARE_ACCELERATION_LABEL" desc="Label for the checkbox that forces Chrome to render via hardware acceleration (GPU) when available.">
       Use hardware acceleration when available
     </message>
     <message name="IDS_SETTINGS_SYSTEM_PROXY_SETTINGS_BUTTON" desc="Text for the button that changes a user's network proxy settings.">
       Change proxy settings
     </message>
   </if>
 </grit-part>