Mojo: Add a utility to compare old mojom_bindings_generator.py output to the current one.

mojo/public/tools/bindings/pylib/mojom_tests/support/run_bindings_generator.py

Index: mojo/public/tools/bindings/pylib/mojom_tests/support/run_bindings_generator.py
diff --git a/mojo/public/tools/bindings/pylib/mojom_tests/support/run_bindings_generator.py b/mojo/public/tools/bindings/pylib/mojom_tests/support/run_bindings_generator.py
new file mode 100644
index 0000000000000000000000000000000000000000..20ef461969923ec9f63d3fedfd921f713f1c8bd2
--- /dev/null
+++ b/mojo/public/tools/bindings/pylib/mojom_tests/support/run_bindings_generator.py
@@ -0,0 +1,47 @@
+# Copyright 2014 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.
+
+import os.path
+from subprocess import check_call
+import sys
+
+
+def RunBindingsGenerator(out_dir, root_dir, mojom_file, extra_flags=None):
+  out_dir = os.path.abspath(out_dir)
+  root_dir = os.path.abspath(root_dir)
+  mojom_file = os.path.abspath(mojom_file)
+
+  # The mojom file should be under the root directory somewhere.
+  assert mojom_file.startswith(root_dir)
+  mojom_reldir = os.path.dirname(os.path.relpath(mojom_file, root_dir))
+
+  # TODO(vtl): Abstract out the "main" functions, so that we can just import
+  # the bindings generator (which would be more portable and easier to use in
+  # tests).
+  this_dir = os.path.dirname(os.path.abspath(__file__))
+  # We're in src/mojo/public/tools/bindings/pylib/mojom_tests/support;
+  # mojom_bindings_generator.py is in .../bindings.
+  bindings_generator = os.path.join(this_dir, os.pardir, os.pardir, os.pardir,
+                                    "mojom_bindings_generator.py")
+
+  args = ["python", bindings_generator,
+          "-o", os.path.join(out_dir, mojom_reldir)]
+  if extra_flags:
+    args.extend(extra_flags)
+  args.append(mojom_file)
+
+  check_call(args)
+
+
+def main(argv):
+  if len(argv) < 4:
+    print "usage: %s out_dir root_dir mojom_file [extra_flags]" % argv[0]
+    return 1
+
+  RunBindingsGenerator(argv[1], argv[2], argv[3], extra_flags=argv[4:])
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))