Remove the deprecated ValueSerializer::ReadHeader overload with no context parameter.

Remove the deprecated ValueSerializer::ReadHeader overload with no context parameter.

Several weeks have now passed since it was deprecated; Chromium does not
call it.

BUG=chromium:148757
Committed: https://crrev.com/5d3ce7ea4fa299f8463ee15282fa986b50702cd8
Cr-Commit-Position: refs/heads/master@{#40945}

[jbroman, 2016-11-04 16:47:09]

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

[commit-bot: I haz the power, 2016-11-04 16:47:19]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[jbroman, 2016-11-04 17:05:38]

jbroman@chromium.org changed reviewers:
+ jochen@chromium.org

[commit-bot: I haz the power, 2016-11-04 17:19:45]

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

[commit-bot: I haz the power, 2016-11-04 17:19:46]

Dry run: This issue passed the CQ dry run.

[jochen (gone - plz use gerrit), 2016-11-12 23:08:54]

lgtm

[jbroman, 2016-11-13 02:42:41]

The CQ bit was checked by jbroman@chromium.org

[commit-bot: I haz the power, 2016-11-13 02:42:48]

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, 2016-11-13 03:09:50]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-11-17 22:31:38]

Description was changed from

==========
Remove the deprecated ValueSerializer::ReadHeader overload with no context
parameter.

Several weeks have now passed since it was deprecated; Chromium does not
call it.

BUG=chromium:148757
==========

to

==========
Remove the deprecated ValueSerializer::ReadHeader overload with no context
parameter.

Several weeks have now passed since it was deprecated; Chromium does not
call it.

BUG=chromium:148757

Committed: https://crrev.com/5d3ce7ea4fa299f8463ee15282fa986b50702cd8
Cr-Commit-Position: refs/heads/master@{#40945}
==========

[commit-bot: I haz the power, 2016-11-17 22:31:39]

Patchset 1 (id:??) landed as
https://crrev.com/5d3ce7ea4fa299f8463ee15282fa986b50702cd8
Cr-Commit-Position: refs/heads/master@{#40945}