ChromeOS OOBE: fix focus flow in MD-OOBE.

chrome/browser/resources/chromeos/login/oobe_welcome_dialog.html

Index: chrome/browser/resources/chromeos/login/oobe_welcome_dialog.html
diff --git a/chrome/browser/resources/chromeos/login/oobe_welcome_dialog.html b/chrome/browser/resources/chromeos/login/oobe_welcome_dialog.html
index 6b2eacb05142180815fdb707933ff580e6b9b3e0..3a6be4462cf150fcb6660698ca8c8694a5bbf252 100644
--- a/chrome/browser/resources/chromeos/login/oobe_welcome_dialog.html
+++ b/chrome/browser/resources/chromeos/login/oobe_welcome_dialog.html
@@ -20,22 +20,24 @@
         <img id="welcomeIllustration" src="images/welcome_illustration_2x.png">
         <div class="flex"></div>
         <div id="buttons" class="layout horizontal center">
-          <oobe-welcome-secondary-button icon="icons:language"
-              on-tap="onLanguageClicked_"
+          <oobe-welcome-secondary-button id="languageSelectionButton"
+              icon="icons:language" on-tap="onLanguageClicked_"
               aria-label="[[formatMessage_('languageButtonLabel',
                   currentLanguage)]]">
             <div>[[currentLanguage]]</div>
           </oobe-welcome-secondary-button>
-          <oobe-welcome-secondary-button icon="icons:accessibility"
-              on-tap="onAccessibilityClicked_">
+          <oobe-welcome-secondary-button id="accessibilitySettingsButton"
+              icon="icons:accessibility" on-tap="onAccessibilityClicked_">
             <div>$i18n{accessibilityLink}</div>
           </oobe-welcome-secondary-button>
-          <oobe-welcome-secondary-button icon="oobe-welcome-64:timezone"
-              on-tap="onTimezoneClicked_" hidden="[[!timezoneButtonVisible]]">
+          <oobe-welcome-secondary-button id="timezoneSettingsButton"
+              icon="oobe-welcome-64:timezone" on-tap="onTimezoneClicked_"
+              hidden="[[!timezoneButtonVisible]]">
             <div>$i18n{timezoneButtonText}</div>
           </oobe-welcome-secondary-button>
           <div class="flex"></div>
-          <oobe-text-button inverse on-tap="onNextClicked_">
+          <oobe-text-button id="welcomeNextButton"
+              inverse on-tap="onNextClicked_">
             <div>$i18n{welcomeNextButtonText}</div>
           </oobe-text-button>
         </div>