Added an rdb wrapper and use it to time CheckChangeOn{Commit, Upload} from every PRESUBMIT.py file, then reports the results to ResultSink.

Bug: http://crbug.com/1107588

Change-Id: I9bc8a18ba615a76f3e0611eae5b2c4adc5924276
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2242097
Commit-Queue: Saagar Sanghavi <saagarsanghavi@google.com>
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Garrett Beaty <gbeaty@chromium.org>