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/tools/clang/plugins/tests/inline_copy_ctor.h b/tools/json_schema_compiler/test/idl_namespace_all_platforms.idl
similarity index 52%
copy from tools/clang/plugins/tests/inline_copy_ctor.h
copy to tools/json_schema_compiler/test/idl_namespace_all_platforms.idl
index 619a18392bfe18a77930548b3ecb25ca55a9e9ca..6aa58c5b3383a2deb5bfe3f44ce09ea3364cb646 100644
--- a/tools/clang/plugins/tests/inline_copy_ctor.h
+++ b/tools/json_schema_compiler/test/idl_namespace_all_platforms.idl
@@ -1,12 +1,10 @@
-// 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.
-
-struct C {
-  C();
-  ~C();
-
-  static C foo() { return C(); }
-
-  int a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p , q, r, s, t, u, v, w, x;
-};
+// 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.
+
+[platforms=("chromeos", "chromeos_touch", "linux", "mac", "win")]
+namespace idl_namespace_all_platforms {
+
+};