Allow IDL schemas to have comments on callback functions

tools/json_schema_compiler/test/idl_basics.idl

 // 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.
 
 // Tests a variety of basic API definition features.
 
 [internal] namespace idl_basics {
   // Enum description
   enum EnumType {
     name1,
     name2
   };
 
   dictionary MyType1 {
     // This comment tests "double-quotes".
     [legalValues=(1,2)] long x;
     DOMString y;
   };
 
   dictionary MyType2 {
     DOMString x;
   };
 
   callback Callback1 = void();
   callback Callback2 = void(long x);
   callback Callback3 = void(MyType1 arg);
   callback Callback4 = void(MyType2[] arg);
   callback Callback5 = void(EnumType type);
+  // A comment on a callback.
+  // |x|: A parameter.
+  callback Callback6 = void(long x);
+  // |x|: A parameter with no parent callback.

[asargent_no_longer_on_chrome, 2012/11/01 16:55:37]

nit: I don't quite understand the "with no parent callback" part of this
comment. Did you mean "with no parent comment"? (That's still confusing though,
because it looks like your function18 test below does use Callback7 both with
and without a parent comment.

[cduvall, 2012/11/01 22:56:01]

Done, should be more clear now.

+  callback Callback7 = void(long x);
 
   interface Functions {
     static void function1();
     static void function2(long x);
     // This comment should appear in the documentation,
     // despite occupying multiple lines.
     //
     // |arg|: So should this comment
     // about the argument.
     // <em>HTML</em> is fine too.
@@ skipping 14 matching lines @@
     static void function11(MyType1[] arg);
 
     static void function12(Callback4 cb);
 
     static void function13(EnumType type, Callback5 cb);
     static void function14(EnumType[] types);
 
     // "switch" is a reserved word and should cause a C++ compile error if we
     // emit code for this declaration.
     [nocompile] static void function15(long switch);
+
+    static void function16(Callback6 cb);
+    static void function17(Callback7 cb);
+    // |cb|: Override callback comment.
+    static void function18(Callback7 cb);
   };
 
   interface Events {
     static void onFoo1();
     static void onFoo2(long x);
     static void onFoo2(MyType1 arg);
     static void onFoo3(EnumType type);
   };
 };