ChromeOS OOBE: fix focus flow in MD-OOBE.

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

Index: chrome/browser/resources/chromeos/login/oobe_welcome_dialog.js
diff --git a/chrome/browser/resources/chromeos/login/oobe_welcome_dialog.js b/chrome/browser/resources/chromeos/login/oobe_welcome_dialog.js
index da888ecdc66b912b8a7f34afbcd19ba28b863a83..40ab10607c1f2e007a7f8ad2fba3d8de3867cf92 100644
--- a/chrome/browser/resources/chromeos/login/oobe_welcome_dialog.js
+++ b/chrome/browser/resources/chromeos/login/oobe_welcome_dialog.js
@@ -12,6 +12,7 @@ Polymer({
       type: String,
       value: '',
     },
+
     /**
      * Controls visibility of "Timezone" button.
      */
@@ -21,22 +22,49 @@ Polymer({
     },
   },
 
+  /**
+   * This is stored ID of currently focused element to restore id on returns
+   * to this dialog from Language / Timezone Selection dialogs.
+   */
+  focusedElement_: 'languageSelectionButton',
+
   onLanguageClicked_: function() {
+    this.focusedElement_ = "languageSelectionButton";
     this.fire('language-button-clicked');
   },
 
   onAccessibilityClicked_: function() {
+    this.focusedElement_ = "accessibilitySettingsButton";
     this.fire('accessibility-button-clicked');
   },
 
   onTimezoneClicked_: function() {
+    this.focusedElement_ = "timezoneSettingsButton";
     this.fire('timezone-button-clicked');
   },
 
   onNextClicked_: function() {
+    this.focusedElement_ = "welcomeNextButton";
     this.fire('next-button-clicked');
   },
 
+  attached: function() {
+    this.focus();
+  },
+
+  focus: function() {
+    var focusedElement = this.$[this.focusedElement_];
+    if (focusedElement)
+      focusedElement.focus();
+  },
+
+  /**
+    * This is called from oobe_welcome when this dialog is shown.
+    */
+  show: function() {
+    this.focus();
+  },
+
   /**
     * This function formats message for labels.
     * @param String label i18n string ID.