The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/00b052df240f35c01b6d68b9ee2963482deca06d

commit 00b052df240f35c01b6d68b9ee2963482deca06d
Author: Yuke Liao <liaoyuke@chromium.org>
Date: Mon Sep 11 20:30:29 2017

[Coverage] Support skipping testing and reusing specified profile data.

The code coverage script relies on running the test suite to generate
a profile data file, however, it's quite time consuming to run some of
the test suites, take ios_chrome_unittests for example, it take about
2 minutes to run.

This CL adds an option to the cmd argument to skip running tests to
generate the profile data file, instead, reuse the one specified in
cmd argument.

Bug:  763962 
Change-Id: Ie3f6b2bb84807bc2ba47e9af5784df37b8ff8694
Reviewed-on: https://chromium-review.googlesource.com/661075
Reviewed-by: Mike Baxley <baxley@chromium.org>
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501022}
[modify] https://crrev.com/00b052df240f35c01b6d68b9ee2963482deca06d/ios/tools/coverage/coverage.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4ee3313434e0b3ec2af1fa72346a387b338c2c44

commit 4ee3313434e0b3ec2af1fa72346a387b338c2c44
Author: Yuke Liao <liaoyuke@chromium.org>
Date: Tue Sep 12 20:51:57 2017

[Coverage] Add an existence assertion for reused prodata file.

This CL adds an assertion to make sure that the user specified profile
data file exists.

Bug:  763962 
Change-Id: I2a8830ad8fc7ca1a5f91e739ba3107ac70e3a2eb
Reviewed-on: https://chromium-review.googlesource.com/662237
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: Mike Baxley <baxley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501390}
[modify] https://crrev.com/4ee3313434e0b3ec2af1fa72346a387b338c2c44/ios/tools/coverage/coverage.py