metrics: Report bot metrics if DEPOT_TOOLS_REPORT_BUILD is set

If the DEPOT_TOOLS_REPORT_BUILD envvar is set, Depot Tools will
report information about the builder running the command
(e.g. buildbucket project, bucket, builder and build id).

It will also authenticate to the metrics server, and ignore any
requests not made by ChOps service accounts.

Change-Id: I078a4c2170b4226086c42f289fa449bdebc87179
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2861213
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@google.com>

upload_metrics.py

@@ -1,21 +1,27 @@
-#!/usr/bin/env python
+#!/usr/bin/env vpython3
 # Copyright (c) 2018 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
 import sys
+import urllib.error
+import urllib.request
 
-from third_party.six.moves import urllib
-from third_party.six.moves import input # pylint: disable=redefined-builtin
-
+import auth
 import metrics_utils
 
-
 def main():
   metrics = input()
   try:
-    urllib.request.urlopen(
-        metrics_utils.APP_URL + '/upload', metrics.encode('utf-8'))
+    headers = {}
+    if 'bot_metrics' in metrics:
+      token = auth.Authenticator().get_access_token().token
+      headers = {'Authorization': 'Bearer ' + token}
+    urllib.request.urlopen(urllib.request.Request(
+        url=metrics_utils.APP_URL + '/upload',
+        data=metrics.encode('utf-8'),
+        headers=headers))
   except (urllib.error.HTTPError, urllib.error.URLError):
     pass