GceHost: add set_instance_metadata method

BUG=b:20157466
TEST=cloud_CloudConfigServer

Change-Id: Id560a076201f3ecde038256194a8d23b6b6fd727
Reviewed-on: https://chromium-review.googlesource.com/319818
Commit-Ready: Andrey Ulanov <andreyu@google.com>
Tested-by: Andrey Ulanov <andreyu@google.com>
Reviewed-by: Andy Zheng <qzheng@google.com>
1 file changed