Bug 1457146 - Add policy for turning the new tab page off r=Felipe,flod

Differential Revision: https://phabricator.services.mozilla.com/D25675

--HG--
extra : moz-landing-system : lando

browser/components/enterprisepolicies/Policies.jsm

@@ -680,6 +680,12 @@ var Policies = {
     },
   },
 
+  "NewTabPage": {
+    onBeforeAddons(manager, param) {
+      setAndLockPref("browser.newtabpage.enabled", param);
+    },
+  },
+
   "NoDefaultBookmarks": {
     onProfileAfterChange(manager, param) {
       if (param) {

browser/components/enterprisepolicies/schemas/policies-schema.json

@@ -393,6 +393,10 @@
       "type": "boolean"
     },
 
+    "NewTabPage": {
+      "type": "boolean"
+    },
+
     "NoDefaultBookmarks": {
       "type": "boolean"
     },

browser/components/enterprisepolicies/tests/browser/browser_policies_simple_pref_policies.js

@@ -268,6 +268,16 @@ const POLICIES_TESTS = [
       "browser.newtabpage.activity-stream.asrouter.userprefs.cfr.features": false,
     },
   },
+
+  // POLICY: NewTabPage
+  {
+    policies: {
+      "NewTabPage": false,
+    },
+    lockedPrefs: {
+      "browser.newtabpage.enabled": false,
+    },
+  },
 ];
 
 add_task(async function test_policy_remember_passwords() {

browser/locales/en-US/browser/policies/policies-descriptions.ftl

@@ -99,6 +99,8 @@ policy-InstallAddonsPermission = Allow certain websites to install add-ons.
 
 policy-NetworkPrediction = Enable or disable network prediction (DNS prefetching).
 
+policy-NewTabPage = Enable or disable the New Tab page.
+
 policy-NoDefaultBookmarks = Disable creation of the default bookmarks bundled with { -brand-short-name }, and the Smart Bookmarks (Most Visited, Recent Tags). Note: this policy is only effective if used before the first run of the profile.
 
 policy-OfferToSaveLogins = Enforce the setting to allow { -brand-short-name } to offer to remember saved logins and passwords. Both true and false values are accepted.