utils: ipc: import mojo

Import mojo from the Chromium repository, so that we can use it for
generating code for the IPC mechanism. The commit from which this was
taken is:
a079161ec8c6907b883f9cb84fc8c4e7896cb1d0 "Add PPAPI constructs for
sending focus object to PdfAccessibilityTree"

This tree has been pruned to remove directories that didn't have any
necessary code:
- mojo/* except for mojo/public
  - mojo core, docs, and misc files
- mojo/public/* except for mojo/public/{tools,LICENSE}
  - language bindings for IPC, tests, and some mojo internals
- mojo/public/tools/{fuzzers,chrome_ipc}
- mojo/public/tools/bindings/generators
  - code generation for other languages

No files were modified.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Acked-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

utils/ipc/mojo/public/tools/run_all_python_unittests.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python
+# Copyright 2020 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
+import sys
+
+_TOOLS_DIR = os.path.dirname(__file__)
+_MOJOM_DIR = os.path.join(_TOOLS_DIR, 'mojom')
+_SRC_DIR = os.path.join(_TOOLS_DIR, os.path.pardir, os.path.pardir,
+                        os.path.pardir)
+
+# Ensure that the mojom library is discoverable.
+sys.path.append(_MOJOM_DIR)
+
+# Help Python find typ in //third_party/catapult/third_party/typ/
+sys.path.append(
+    os.path.join(_SRC_DIR, 'third_party', 'catapult', 'third_party', 'typ'))
+import typ
+
+
+def Main():
+  return typ.main(top_level_dir=_MOJOM_DIR)
+
+
+if __name__ == '__main__':
+  sys.exit(Main())