Add a check for "Google Inc." copyright

For third-party projects where we are pushing code upstream we
should assign copyright to "Google Inc." rather than "The Chromium
OS" authors.

See the Chromium OS Kernel Faq and "How To Open Source Google
Code" on the OSPO site for details.

BUG=none
TEST=Tested in a follow-up CL with good/bad copyrights for a
     GPLv2 project

Change-Id: I5abd5a089a4d45a4c6d8d70c5ece337d7383e758
Reviewed-on: https://gerrit.chromium.org/gerrit/42569
Commit-Queue: David Hendricks <dhendrix@chromium.org>
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Tested-by: David Hendricks <dhendrix@chromium.org>
Reviewed-by: David James <davidjames@chromium.org>
diff --git a/pre-upload.py b/pre-upload.py
index 1ca755c..4879642 100755
--- a/pre-upload.py
+++ b/pre-upload.py
@@ -358,6 +358,16 @@
   return _verify_header_content(commit, LICENSE_HEADER, FAIL_MSG)
 
 
+def _check_google_copyright(project, commit):
+  """Verifies Google Inc. as copyright holder."""
+  LICENSE_HEADER = (
+     r".* Copyright 20[-0-9]{2,7} Google Inc\."
+  )
+  FAIL_MSG = "Copyright must match"
+
+  return _verify_header_content(commit, LICENSE_HEADER, FAIL_MSG)
+
+
 # Project-specific hooks