Statically allocate extension download lookups.

Statically allocate extension download lookups.

This avoids building singleton maps to convert between strings and download
enums. The maps are now pre-sorted lists of static data.

Unit tests are added to ensure the data is properly sorted.

[brettw, 2017-06-28 23:51:41]

Better tests

[brettw, 2017-06-28 23:52:04]

Description was changed from

==========
Statically allocate extension download strings.

This avoids building singleton maps to convert between strings and download
enums. The maps are now pre-sorted lists of static data.

Unit tests are added to ensure the data is properly sorted.
==========

to

==========
Statically allocate extension download lookups.

This avoids building singleton maps to convert between strings and download
enums. The maps are now pre-sorted lists of static data.

Unit tests are added to ensure the data is properly sorted.
==========

[brettw, 2017-06-28 23:52:04]

brettw@chromium.org changed reviewers:
+ benjhayden@chromium.org

[brettw, 2017-06-28 23:53:10]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-06-28 23:53:47]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-06-29 00:04:42]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-06-29 00:04:43]

Dry run: Try jobs failed on following builders:
  linux_chromium_tsan_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[brettw, 2017-06-29 00:06:33]

Actually, I'm abandoning this, there are some constexpr problems that I think
are due to out-of-date libc++ and I've spent too much time on this (it was a
request from a comment on https://codereview.chromium.org/2829163004/).

If you like it and have the inclination, feel free to pick it up.