Re-land: Update json_schema_compiler to handle the Automation extension API

tools/json_schema_compiler/idl_schema.py

Index: tools/json_schema_compiler/idl_schema.py
diff --git a/tools/json_schema_compiler/idl_schema.py b/tools/json_schema_compiler/idl_schema.py
index 58efe28598f1660e9f4481e412f30fa715195668..fcad49bef4e2fde5eb75f8fa359c5ee2d97e3266 100755
--- a/tools/json_schema_compiler/idl_schema.py
+++ b/tools/json_schema_compiler/idl_schema.py
@@ -50,13 +50,20 @@ def ProcessComment(comment):
 
   Returns: A tuple that looks like:
     (
-      "The processed comment, minus all |parameter| mentions.",
+      "The processed comment, minus all |parameter| mentions and jsexterns.",
+      "Any block wrapped in <jsexterns></jsexterns>.",
       {
         'parameter_name_1': "The comment that followed |parameter_name_1|:",
         ...
       }
     )
   '''
+  jsexterns = None
+  match = re.search('<jsexterns>(.*)</jsexterns>', comment, re.DOTALL)
+  if match:
+    jsexterns = match.group(1).strip()
+    comment = comment[:match.start()] + comment[match.end():]
+
   def add_paragraphs(content):
     paragraphs = content.split('\n\n')
     if len(paragraphs) < 2:
@@ -85,7 +92,7 @@ def ProcessComment(comment):
         add_paragraphs(comment[param_comment_start:param_comment_end].strip())
         .replace('\n', ''))
 
-  return (parent_comment, params)
+  return (parent_comment, jsexterns, params)
 
 
 class Callspec(object):
@@ -195,8 +202,10 @@ class Member(object):
     parameter_comments = OrderedDict()
     for node in self.node.GetChildren():
       if node.cls == 'Comment':
-        (parent_comment, parameter_comments) = ProcessComment(node.GetName())
+        (parent_comment, jsexterns, parameter_comments) = ProcessComment(
+            node.GetName())
         properties['description'] = parent_comment
+        properties['jsexterns'] = jsexterns
       elif node.cls == 'Callspec':
         name, parameters, return_type = (Callspec(node, parameter_comments)
                                          .process(callbacks))