js_externs_generator.py: Generate JS externs for top-level properties.

Previously top-level properties like chrome.runtime.id or
chrome.runtime.lastError where ignored by js_externs_generator.py
and were not reflected in the generated JS externs files.

Fixed: 1085641
Change-Id: I6a5719830f5c0945ca0b26c5c347bd3341b379c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2213205
Commit-Queue: dpapad <dpapad@chromium.org>
Auto-Submit: dpapad <dpapad@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Cr-Commit-Position: refs/heads/master@{#772370}

tools/json_schema_compiler/js_externs_generator.py

@@ -53,6 +53,9 @@ class _Generator(object):
     for js_type in self._namespace.types.values():
       self._AppendType(c, js_type)
 
+    for prop in self._namespace.properties.values():
+      self._AppendProperty(c, prop)
+
     for function in self._namespace.functions.values():
       self._AppendFunction(c, function)
 
@@ -162,12 +165,24 @@ class _Generator(object):
 
     c.Append('@typedef {')
     if properties:
-        self._js_util.AppendObjectDefinition(
-                c, self._namespace.name, properties, new_line=False)
+      self._js_util.AppendObjectDefinition(c,
+                                           self._namespace.name,
+                                           properties,
+                                           new_line=False)
     else:
-        c.Append('Object', new_line=False)
+      c.Append('Object', new_line=False)
     c.Append('}', new_line=False)
 
+  def _AppendProperty(self, c, prop):
+    """Appends the code representing a top-level property, including its
+       documentation. For example:
+
+       /** @type {string} */
+       chrome.runtime.id;
+    """
+    self._AppendTypeJsDoc(c, prop.type_, prop.optional)
+    c.Append()
+
   def _AppendFunction(self, c, function):
     """Appends the code representing a function, including its documentation.
        For example:

tools/json_schema_compiler/js_externs_generator_test.py

@@ -65,6 +65,10 @@ namespace fakeApi {
 
   callback OptionalParamCallback = void(optional Qux qux);
 
+  interface Properties {
+    static DOMString lastError();
+  };
+
   interface Functions {
     // Does something exciting! And what's more, this is a multiline function
     // comment! It goes onto multiple lines!
@@ -193,6 +197,12 @@ chrome.fakeApi.Qux.prototype.go = function() {};
 chrome.fakeApi.Qux.prototype.stop = function() {};
 
 
+/**
+ * @type {string}
+ * @see https://developer.chrome.com/extensions/fakeApi#type-lastError
+ */
+chrome.fakeApi.lastError;
+
 /**
  * Does something exciting! And what's more, this is a multiline function
  * comment! It goes onto multiple lines!
@@ -336,6 +346,12 @@ fake_json = """// Copyright 2014 The Chromium Authors. All rights reserved.
         "additionalProperties": {"type": "string"}
       }
     ],
+    "properties": {
+      "lastError": {
+        "type": "string",
+        "description": "The lastError."
+      }
+    },
     "functions": [ {
       "name": "funcWithInlineObj",
       "type": "function",
@@ -429,6 +445,13 @@ chrome.fakeJson.CrazyEnum = {
  */
 chrome.fakeJson.CrazyObject;
 
+/**
+ * The lastError.
+ * @type {string}
+ * @see https://developer.chrome.com/extensions/fakeJson#type-lastError
+ */
+chrome.fakeJson.lastError;
+
 /**
  * @param {{
  *   foo: (boolean|undefined),