Add minimum TLS version control to about:flags and Finch gate it.

Add minimum TLS version control to about:flags and Finch gate it.

This change adds an entry to about:flags to control the minimum TLS version as
requested by Darin. This will allow Android and ChromeOS users to reenable
SSLv3 in Chrome 40 if they need to.

Additionally, this gates the SSLv3 disabling with Finch. At the moment the
experiment doesn't actually exist and so will always return the empty string.
However, should we need to, we can define it and put everyone in the Enabled
group.

BUG=427671, 419870
Committed: https://crrev.com/0a4a16346d0a921949ad8f423934350a3b504e70
Cr-Commit-Position: refs/heads/master@{#302754}

[agl, 2014-10-31 20:56:04]

agl@chromium.org changed reviewers:
+ asvitkine@chromium.org, rsleevi@chromium.org

[Alexei Svitkine, 2014-10-31 21:02:14]

lgtm

[agl, 2014-11-03 22:09:21]

agl@chromium.org changed reviewers:
+ rch@chromium.org

[agl, 2014-11-03 22:09:22]

+rch, randomly, because rsleevi is away and because the most questionable part
is the Finch code.

[Ryan Hamilton, 2014-11-03 23:02:52]

If you're paranoid, you can run with -force-fieldtrials=SSLv3/Enabled/ to ensure
that your code does what you want.  That being said, this LGTM.

https://codereview.chromium.org/693963003/diff/20001/chrome/browser/net/ssl_c...
File chrome/browser/net/ssl_config_service_manager_pref.cc (right):

https://codereview.chromium.org/693963003/diff/20001/chrome/browser/net/ssl_c...
chrome/browser/net/ssl_config_service_manager_pref.cc:279:
base::FieldTrialList::FindFullName("SSLv3");
Nit: it looks like this will all fit on one line?

[agl, 2014-11-04 19:00:32]

https://codereview.chromium.org/693963003/diff/20001/chrome/browser/net/ssl_c...
File chrome/browser/net/ssl_config_service_manager_pref.cc (right):

https://codereview.chromium.org/693963003/diff/20001/chrome/browser/net/ssl_c...
chrome/browser/net/ssl_config_service_manager_pref.cc:279:
base::FieldTrialList::FindFullName("SSLv3");
On 2014/11/03 23:02:52, Ryan Hamilton wrote:
> Nit: it looks like this will all fit on one line?

Done.

[agl, 2014-11-04 19:00:35]

The CQ bit was checked by agl@chromium.org

[I haz the power (commit-bot), 2014-11-04 19:02:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/693963003/40001

[agl, 2014-11-04 19:11:09]

The CQ bit was unchecked by agl@chromium.org

[agl, 2014-11-04 19:12:52]

The CQ bit was checked by agl@chromium.org

[I haz the power (commit-bot), 2014-11-04 19:14:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/693963003/60001

[I haz the power (commit-bot), 2014-11-04 19:39:56]

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

[I haz the power (commit-bot), 2014-11-04 19:39:56]

Try jobs failed on following builders:
  linux_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu_trigger...)

[agl, 2014-11-04 19:41:04]

The CQ bit was checked by agl@chromium.org

[I haz the power (commit-bot), 2014-11-04 19:42:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/693963003/80001

[I haz the power (commit-bot), 2014-11-04 20:06:15]

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

[I haz the power (commit-bot), 2014-11-04 20:06:16]

Try jobs failed on following builders:
  linux_gpu_triggered_tests on tryserver.chromium.gpu
(http://build.chromium.org/p/tryserver.chromium.gpu/builders/linux_gpu_trigger...)

[agl, 2014-11-05 03:14:40]

The CQ bit was checked by agl@chromium.org

[I haz the power (commit-bot), 2014-11-05 03:15:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/693963003/50007

[I haz the power (commit-bot), 2014-11-05 04:17:14]

Committed patchset #6 (id:50007)

[I haz the power (commit-bot), 2014-11-05 04:18:08]

Patchset 6 (id:??) landed as
https://crrev.com/0a4a16346d0a921949ad8f423934350a3b504e70
Cr-Commit-Position: refs/heads/master@{#302754}