ChromeOS: Update styles of material design OOBE.

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 1620 matching lines @@
   </message>
   <message name="IDS_NETWORK_ENABLE_DEV_FEATURES_LINK" desc="Text shown on continue button" meaning="Link shown on OOBE screens that opens enable debugging features dialog">
     Enable debugging features
   </message>
   <message name="IDS_LANGUAGE_DROPDOWN_TITLE" desc="Title of language selection dropdown menu" meaning="Small title near language dropdown menu suggesting that this is a language selector.">
     Language
   </message>
   <message name="IDS_KEYBOARD_DROPDOWN_TITLE" desc="Title of keyboard selection dropdown menu" meaning="Small title near keyboard dropdown menu suggesting that this is a keyboard layout selector.">
     Keyboard
   </message>
+  <message name="IDS_OOBE_WELCOME_NEXT_BUTTON_TEXT" desc="Text on 'Start to use ChromeOS' button" meaning="This is the text label displayed on the 'Next' button for the first ChromeOS initial device setup screen ('Welcome screen').">
+    Let's go
+  </message>
   <message name="IDS_OOBE_OK_BUTTON_TEXT" desc="Text on 'OK' button" meaning="This is 'OK' text for all 'OK' buttons on ChromeOS initial device setup screens.">
     OK
   </message>
   <message name="IDS_LANGUAGE_SECTION_TITLE" desc="Title of language selection screen" meaning="A title of the dialog where user should select ChromeOS UI language and default keyboard layout during initial device setup.">
     Choose your language &amp; keyboard
   </message>
   <message name="IDS_ACCESSIBILITY_SECTION_TITLE" desc="Title of accessibility options screen" meaning="A title of the dialog where user can control ChromeOS UI accessibility (like large cursor or screen reader) options during initial device setup.">
     Accessibility settings
   </message>
   <message name="IDS_ACCESSIBILITY_SECTION_HINT" desc="Under-title line on the accessibility options screen" meaning="A hint to the user that these settings help to make device more usable.">
@@ skipping 5286 matching lines @@
   <message name="IDS_CRITICALLY_LOW_DISK_NOTIFICATION_TITLE" desc="Title of the notification warning users that they are critically low on disk space.">
     Device disk space critically low
   </message>
   <message name="IDS_CRITICALLY_LOW_DISK_NOTIFICATION_MESSAGE" desc="Notification text warning users that they are critically low on disk space.">
     Free up disk space or device will become unresponsive.
   </message>
   <message name="IDS_LOW_DISK_NOTIFICATION_BUTTON" desc="Button on the low disk notification to open storage management.">
     Manage storage
   </message>
 </grit-part>