[TTS] Add server control from a field_trial param.

[TTS] Add server control from a field_trial param.

Add support to set the contextual cards integration version
explictly from a field trial param.

This will let us control a server-side feature from the field
trial config and evaluate client usage differences.

BUG=692351
Review-Url: https://codereview.chromium.org/2697513005
Cr-Commit-Position: refs/heads/master@{#450845}
(cherry picked from commit 917adcfaa04e622273c5a64694fa578e03ac58ff)

Review-Url: https://codereview.chromium.org/2700943004 .
Cr-Commit-Position: refs/branch-heads/2987@{#576}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/83cfdcf158a2ce8f9efa5ad68a69dd2e4455cc9e

[Donn Denman, 2017-02-17 17:35:32]

Description was changed from

==========
[TTS] Add server control from a field_trial param.

Add support to set the contextual cards integration version
explictly from a field trial param.

This will let us control a server-side feature from the field
trial config and evaluate client usage differences.

BUG=692351

Review-Url: https://codereview.chromium.org/2697513005
Cr-Commit-Position: refs/heads/master@{#450845}
(cherry picked from commit 917adcfaa04e622273c5a64694fa578e03ac58ff)
==========

to

==========
[TTS] Add server control from a field_trial param.

Add support to set the contextual cards integration version
explictly from a field trial param.

This will let us control a server-side feature from the field
trial config and evaluate client usage differences.

BUG=692351

Review-Url: https://codereview.chromium.org/2697513005
Cr-Commit-Position: refs/heads/master@{#450845}
(cherry picked from commit 917adcfaa04e622273c5a64694fa578e03ac58ff)

Review-Url: https://codereview.chromium.org/2700943004 .
Cr-Commit-Position: refs/branch-heads/2987@{#576}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/83cfdcf158a2ce8f9efa5ad68a69...
==========

[Donn Denman, 2017-02-17 17:35:34]

Committed patchset #1 (id:1) manually as
83cfdcf158a2ce8f9efa5ad68a69dd2e4455cc9e.