--- a/toolkit/components/extensions/ext-runtime.js
+++ b/toolkit/components/extensions/ext-runtime.js
@@ -5,17 +5,16 @@ var { classes: Cc, interfaces: Ci, utils
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 XPCOMUtils.defineLazyModuleGetter(this, "AppConstants",
                                   "resource://gre/modules/AppConstants.jsm");
 
 Cu.import("resource://gre/modules/ExtensionUtils.jsm");
 var {
   EventManager,
   ignoreEvent,
-  runSafe,
 } = ExtensionUtils;
 
 extensions.registerSchemaAPI("runtime", null, (extension, context) => {
   return {
     runtime: {
       onStartup: new EventManager(context, "runtime.onStartup", fire => {
         extension.onStartup = fire;
         return () => {
@@ -64,28 +63,28 @@ extensions.registerSchemaAPI("runtime", 
       },
 
       id: extension.id,
 
       getURL: function(url) {
         return extension.baseURI.resolve(url);
       },
 
-      getPlatformInfo: function(callback) {
+      getPlatformInfo: function() {
         let os = AppConstants.platform;
         if (os == "macosx") {
           os = "mac";
         }
 
         let abi = Services.appinfo.XPCOMABI;
         let [arch] = abi.split("-");
         if (arch == "x86") {
           arch = "x86-32";
         } else if (arch == "x86_64") {
           arch = "x86-64";
         }
 
         let info = {os, arch};
-        runSafe(context, callback, info);
+        return Promise.resolve(info);
       },
     },
   };
 });

--- a/toolkit/components/extensions/schemas/runtime.json
+++ b/toolkit/components/extensions/schemas/runtime.json
@@ -132,16 +132,17 @@
           }
         ]
       },
       {
         "name": "openOptionsPage",
         "unsupported": true,
         "type": "function",
         "description": "<p>Open your Extension's options page, if possible.</p><p>The precise behavior may depend on your manifest's <code>$(topic:optionsV2)[options_ui]</code> or <code>$(topic:options)[options_page]</code> key, or what the browser happens to support at the time.</p><p>If your Extension does not declare an options page, or the browser failed to create one for some other reason, the callback will set $(ref:lastError).</p>",
+        "async": "callback",
         "parameters": [{
           "type": "function",
           "name": "callback",
           "parameters": [],
           "optional": true
         }]
       },
       {
@@ -172,16 +173,17 @@
           "description": "The fully-qualified URL to the resource."
         }
       },
       {
         "name": "setUninstallURL",
         "unsupported": true,
         "type": "function",
         "description": "Sets the URL to be visited upon uninstallation. This may be used to clean up server-side data, do analytics, and implement surveys. Maximum 255 characters.",
+        "async": "callback",
         "parameters": [
           {
             "type": "string",
             "name": "url",
             "maxLength": 255,
             "description": "URL to be opened after the extension is uninstalled. This URL must have an http: or https: scheme. Set an empty string to not open a new tab upon uninstallation."
           },
           {
@@ -200,16 +202,17 @@
         "type": "function",
         "parameters": []
       },
       {
         "name": "requestUpdateCheck",
         "unsupported": true,
         "type": "function",
         "description": "Requests an update check for this app/extension.",
+        "async": "callback",
         "parameters": [
           {
             "type": "function",
             "name": "callback",
             "parameters": [
               {
                 "name": "status",
                 "$ref": "RequestUpdateCheckStatus",
@@ -338,16 +341,17 @@
             ]
           }
         ]
       },
       {
         "name": "getPlatformInfo",
         "type": "function",
         "description": "Returns information about the current platform.",
+        "async": "callback",
         "parameters": [
           {
             "type": "function",
             "name": "callback",
             "description": "Called with results",
             "parameters": [
               {
                 "name": "platformInfo",
@@ -357,16 +361,17 @@
           }
         ]
       },
       {
         "name": "getPackageDirectoryEntry",
         "unsupported": true,
         "type": "function",
         "description": "Returns a DirectoryEntry for the package directory.",
+        "async": "callback",
         "parameters": [
           {
             "type": "function",
             "name": "callback",
             "parameters": [
               {
                 "name": "directoryEntry",
                 "type": "object",