Add "platforms" key in IDL schema compiler.

tools/json_schema_compiler/test/idl_namespace_all_platforms.idl

Index: tools/json_schema_compiler/test/idl_namespace_all_platforms.idl
diff --git a/chrome/test/data/extensions/api_test/webnavigation/getFrame/b.js b/tools/json_schema_compiler/test/idl_namespace_all_platforms.idl
similarity index 51%
copy from chrome/test/data/extensions/api_test/webnavigation/getFrame/b.js
copy to tools/json_schema_compiler/test/idl_namespace_all_platforms.idl
index 425f0e59b89b58dfbf5fc84051df78f9ff1493d0..e056c233adb7a50babbf63d123788c4276008b60 100644
--- a/chrome/test/data/extensions/api_test/webnavigation/getFrame/b.js
+++ b/tools/json_schema_compiler/test/idl_namespace_all_platforms.idl
@@ -1,9 +1,10 @@
-// Copyright (c) 2013 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.
-
-onload = function() {
-  var frame = document.getElementById('frame');
-  frame.parentNode.removeChild(frame);
-  frame = null;
-};
+// Copyright (c) 2013 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.
+
+[platforms=("chromeos", "chromeos_touch", "linux", "mac", "win")]
+namespace idl_namespace_all_platforms {
+
+};