MD Settings: Show "Set date and time" button when relevant

chrome/browser/resources/settings/date_time_page/date_time_page.js

Index: chrome/browser/resources/settings/date_time_page/date_time_page.js
diff --git a/chrome/browser/resources/settings/date_time_page/date_time_page.js b/chrome/browser/resources/settings/date_time_page/date_time_page.js
index ed3992bbfa0345213cfe6c50462335e62a5bc539..12bac0663239705d154de048fbba0e3369f107a8 100644
--- a/chrome/browser/resources/settings/date_time_page/date_time_page.js
+++ b/chrome/browser/resources/settings/date_time_page/date_time_page.js
@@ -89,6 +89,16 @@ Polymer({
         }];
       },
     },
+
+    /**
+     * Whether date and time are settable. Normally the date and time are forced
+     * by network time, so default to false to initially hide the button.
+     * @private
+     */
+    canSetDateTime_: {
+      type: Boolean,
+      value: false,
+    },
   },
 
   observers: [
@@ -100,8 +110,10 @@ Polymer({
     this.addWebUIListener(
         'time-zone-auto-detect-policy',
         this.onTimeZoneAutoDetectPolicyChanged_.bind(this));
-    chrome.send('dateTimePageReady');
+    this.addWebUIListener(
+        'can-set-date-time-changed', this.onCanSetDateTimeChanged_.bind(this));
 
+    chrome.send('dateTimePageReady');
     this.maybeGetTimeZoneList_();
   },
 
@@ -134,6 +146,14 @@ Polymer({
   },
 
   /**
+   * @param {boolean} canSetDateTime Whether date and time are settable.
+   * @private
+   */
+  onCanSetDateTimeChanged_: function(canSetDateTime) {
+    this.canSetDateTime_ = canSetDateTime;
+  },
+
+  /**
    * @param {!Event} e
    * @private
    */
@@ -142,6 +162,11 @@ Polymer({
         'settings.resolve_timezone_by_geolocation', e.target.checked);
   },
 
+  /** @private */
+  onSetDateTimeTap_: function() {
+    chrome.send('showSetDateTimeUI');
+  },
+
   /**
    * @param {settings.TimeZoneAutoDetectPolicy} timeZoneAutoDetectPolicy
    * @return {boolean}