[signin] Disable signin-allowed toggle for sync users

When the user is signed in and syncing, the signin-allowed
toggle is now disabled.

Note: This CL is adapted from crrev.com/c/1273517 and
removes the hint, i.e. there are no string changes here.

Bug: 892745
Change-Id: I1778115390518860fca4b4f11588d5ca7c7b9210
Reviewed-on: https://chromium-review.googlesource.com/c/1275849Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Commit-Queue: Thomas Tangl <tangltom@chromium.org>
Cr-Commit-Position: refs/heads/master@{#598901}

chrome/browser/resources/settings/privacy_page/BUILD.gn

@@ -37,6 +37,7 @@ js_library("privacy_page") {
     "..:page_visibility",
     "..:route",
     "../controls:settings_toggle_button",
+    "../people_page:sync_browser_proxy",
     "../settings_page:settings_animated_pages",
     "../site_settings:constants",
     "../site_settings:site_data_details_subpage",

chrome/browser/resources/settings/privacy_page/privacy_page.html

@@ -95,7 +95,8 @@
             pref="{{prefs.signin.allowed_on_next_startup}}"
             label="$i18n{signinAllowedTitle}"
             sub-label="$i18n{signinAllowedDescription}"
-            on-settings-boolean-control-change="onSigninAllowedChange_">
+            on-settings-boolean-control-change="onSigninAllowedChange_"
+            disabled="[[syncStatus.signedIn]]">
         </settings-toggle-button>
 </if><!-- not chromeos -->
         <template is="dom-if" if="[[!unifiedConsentEnabled_]]">

chrome/browser/resources/settings/privacy_page/privacy_page.js

@@ -35,6 +35,12 @@ Polymer({
       notify: true,
     },
 
+    /**
+     * The current sync status, supplied by SyncBrowserProxy.
+     * @type {?settings.SyncStatus}
+     */
+    syncStatus: Object,
+
     /**
      * Dictionary defining page visibility.
      * @type {!PrivacyPageVisibility}
@@ -184,6 +190,20 @@ Polymer({
     this.addWebUIListener(
         'onBlockAutoplayStatusChanged',
         this.onBlockAutoplayStatusChanged_.bind(this));
+
+    settings.SyncBrowserProxyImpl.getInstance().getSyncStatus().then(
+        this.handleSyncStatus_.bind(this));
+    this.addWebUIListener(
+        'sync-status-changed', this.handleSyncStatus_.bind(this));
+  },
+
+  /**
+   * Handler for when the sync state is pushed from the browser.
+   * @param {?settings.SyncStatus} syncStatus
+   * @private
+   */
+  handleSyncStatus_: function(syncStatus) {
+    this.syncStatus = syncStatus;
   },
 
   /** @protected */

chrome/test/data/webui/settings/privacy_page_test.js

@@ -146,6 +146,19 @@ cr.define('settings_privacy_page', function() {
         return test_util.whenAttributeIs(
             dialog.$$('#clearBrowsingDataDialog'), 'open', '');
       });
+
+      if (!cr.isChromeOS) {
+        test('signinAllowedToggle', function() {
+          const toggle = page.$.signinAllowedToggle;
+          page.syncStatus = {signedIn: false};
+          // When the user is signed out, the toggle is enabled.
+          assertFalse(toggle.disabled);
+
+          page.syncStatus = {signedIn: true};
+          // When the user is signed in, the toggle is disabled.
+          assertTrue(toggle.disabled);
+        });
+      }
     });
   }