JSON schema compiler can't handle strings as types

chrome/common/extensions/api/experimental.fontSettings.json

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 [
   {
     "namespace": "experimental.fontSettings",
     "types": [
       {
         "id": "FontName",
@@ skipping 148 matching lines @@
         ]
       },
       {
         "name": "clearDefaultFontSize",
         "description": "Clears the default font size set by this extension, if any.",
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "optional": true,
-            "description": "This parameter is currently unused."
+            "description": "This parameter is currently unused.",
+            "properties": {}
           },
           {
             "type": "function",
             "name": "callback",
             "optional": true,
             "parameters": []
           }
         ]
       },
       {
         "name": "getDefaultFontSize",
         "description": "Gets the default font size.",
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "optional": true,
-            "description": "This parameter is currently unused."
+            "description": "This parameter is currently unused.",
+            "properties": {}
           },
           {
             "name": "callback",
             "type": "function",
             "optional": true,
             "parameters": [
               {
                 "name": "details",
                 "type": "object",
                 "properties": {
@@ skipping 30 matching lines @@
         ]
       },
       {
         "name": "clearDefaultFixedFontSize",
         "description": "Clears the default fixed font size set by this extension, if any.",
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "optional": true,
-            "description": "This parameter is currently unused."
+            "description": "This parameter is currently unused.",
+            "properties": {}
           },
           {
             "type": "function",
             "name": "callback",
             "optional": true,
             "parameters": []
           }
         ]
       },
       {
         "name": "getDefaultFixedFontSize",
         "description": "Gets the default size for fixed width fonts.",
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "optional": true,
-            "description": "This parameter is currently unused."
+            "description": "This parameter is currently unused.",
+            "properties": {}
           },
           {
             "name": "callback",
             "type": "function",
             "optional": true,
             "parameters": [
               {
                 "name": "details",
                 "type": "object",
                 "properties": {
@@ skipping 30 matching lines @@
         ]
       },
       {
         "name": "clearMinimumFontSize",
         "description": "Clears the minimum font size set by this extension, if any.",
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "optional": true,
-            "description": "This parameter is currently unused."
+            "description": "This parameter is currently unused.",
+            "properties": {}
           },
           {
             "type": "function",
             "name": "callback",
             "optional": true,
             "parameters": []
           }
         ]
       },
       {
         "name": "getMinimumFontSize",
         "description": "Gets the minimum font size.",
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "optional": true,
-            "description": "This parameter is currently unused."
+            "description": "This parameter is currently unused.",
+            "properties": {}
           },
           {
             "name": "callback",
             "type": "function",
             "optional": true,
             "parameters": [
               {
                 "name": "details",
                 "type": "object",
                 "properties": {
@@ skipping 30 matching lines @@
         ]
       },
       {
         "name": "clearDefaultCharacterSet",
         "description": "Clears the default character set set by this extension, if any.",
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "optional": true,
-            "description": "This parameter is currently unused."
+            "description": "This parameter is currently unused.",
+            "properties": {}
           },
           {
             "type": "function",
             "name": "callback",
             "optional": true,
             "parameters": []
           }
         ]
       },
       {
         "name": "getDefaultCharacterSet",
         "description": "Gets the default character set.",
         "parameters": [
           {
             "name": "details",
             "type": "object",
             "optional": true,
-            "description": "This parameter is currently unused."
+            "description": "This parameter is currently unused.",
+            "properties": {}
           },
           {
             "name": "callback",
             "type": "function",
             "optional": true,
             "parameters": [
               {
                 "name": "details",
                 "type": "object",
                 "properties": {
@@ skipping 133 matching lines @@
                 "$ref": "LevelOfControl",
                 "description": "The level of control this extension has over the setting."
               }
             }
           }
         ]
       }
     ]
   }
 ]