Made --filter-string optional for emma_coverage.

Made --filter-string optional for emma_coverage.

If we set emma_coverage as true, and do not set --filter-string in
args.gn, build will fail because --filter-string is mandatory. In this
cl, I am making --filter-string optional for emma_coverage.

BUG=

Committed: https://crrev.com/6a18734145371ec315fb356119e63fb3c0661437
Cr-Commit-Position: refs/heads/master@{#388413}

[BigBossZhiling, 2016-04-20 01:24:13]

hzl@google.com changed reviewers:
+ jbudorick@chromium.org

[BigBossZhiling, 2016-04-20 01:24:44]

Please take a look, John.

[jbudorick, 2016-04-20 01:25:38]

lgtm

[BigBossZhiling, 2016-04-20 01:32:52]

The CQ bit was checked by hzl@google.com

[commit-bot: I haz the power, 2016-04-20 01:33:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1905523002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1905523002/1

[commit-bot: I haz the power, 2016-04-20 02:56:31]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-04-22 19:20:21]

Description was changed from

==========
Made --filter-string optional for emma_coverage.

If we set emma_coverage as true, and do not set --filter-string in
args.gn, build will fail because --filter-string is mandatory. In this
cl, I am making --filter-string optional for emma_coverage.

BUG=
==========

to

==========
Made --filter-string optional for emma_coverage.

If we set emma_coverage as true, and do not set --filter-string in
args.gn, build will fail because --filter-string is mandatory. In this
cl, I am making --filter-string optional for emma_coverage.

BUG=

Committed: https://crrev.com/6a18734145371ec315fb356119e63fb3c0661437
Cr-Commit-Position: refs/heads/master@{#388413}
==========

[commit-bot: I haz the power, 2016-04-22 19:20:22]

Patchset 1 (id:??) landed as
https://crrev.com/6a18734145371ec315fb356119e63fb3c0661437
Cr-Commit-Position: refs/heads/master@{#388413}