Reland "Adding an exclusion list to the coverage wrapper script."

This is a reland of 6b7213a45382f01ac0a2efec1015545bd051da89

Original change's description:
> Adding an exclusion list to the coverage wrapper script.
> 
> The script now assumes GN adds coverage flags to the cflags for each
> source file. The script removes the flag if the file is in an exclusion
> list, or if `--files-to-instrument` is set it will also remove flags if
> the file is not listed in that argument.
> 
> The script supports multiple exclusion lists that can be selected with
> the `--target-os` flag.
> 
> It's expected that GN will set these flags correctly and invoke the
> script in all coverage builds. http://crrev.com/c/1496002 does that.
> 
> 
> Bug: 918215
> Change-Id: I4454f67067a083581f31a22cfef85368825789f9
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1495994
> Commit-Queue: Sajjad Mirza <sajjadm@google.com>
> Reviewed-by: Max Moroz <mmoroz@chromium.org>
> Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
> Reviewed-by: Roberto Carrillo <robertocn@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#637892}

Bug: 918215
Change-Id: I1254d288ff263ff94c46b46e6be99738e31b9574
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1506974
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: Max Moroz <mmoroz@chromium.org>
Commit-Queue: Sajjad Mirza <sajjadm@google.com>
Cr-Commit-Position: refs/heads/master@{#638362}
1 file changed