[Sync] Deprecate sync session page state field

[Sync] Deprecate sync session page state field

This field was never written to, and should not be read from. Deprecate it
and remove uses from SerializedNavigationEntry.

BUG=546769
Committed: https://crrev.com/2d7e84c9c92f4f93efbb55aadf70d4f532574167
Cr-Commit-Position: refs/heads/master@{#355855}

[Nicolas Zea, 2015-10-23 00:00:41]

zea@chromium.org changed reviewers:
+ maxbogue@chromium.org, sky@chromium.org

[Nicolas Zea, 2015-10-23 00:00:42]

+Scott, as it looks like Marja is out. PTAL at components/sessions changes.

+Max for sync changes.

[maxbogue, 2015-10-23 00:53:29]

https://codereview.chromium.org/1424493002/diff/1/sync/protocol/session_speci...
File sync/protocol/session_specifics.proto (right):

https://codereview.chromium.org/1424493002/diff/1/sync/protocol/session_speci...
sync/protocol/session_specifics.proto:102: // optional string state = 5;  //
obsolete.
Is it customary to comment out deprecated fields like this in Chromium? I've
only ever seen it done by adding [deprecated = true] elsewhere. Or removing the
field entirely if the proto is never stored, which I don't think applies here.

[Nicolas Zea, 2015-10-23 01:39:44]

On 2015/10/23 00:53:29, maxbogue wrote:
>
https://codereview.chromium.org/1424493002/diff/1/sync/protocol/session_speci...
> File sync/protocol/session_specifics.proto (right):
> 
>
https://codereview.chromium.org/1424493002/diff/1/sync/protocol/session_speci...
> sync/protocol/session_specifics.proto:102: // optional string state = 5;  //
> obsolete.
> Is it customary to comment out deprecated fields like this in Chromium? I've
> only ever seen it done by adding [deprecated = true] elsewhere. Or removing
the
> field entirely if the proto is never stored, which I don't think applies here.

Right, we use it when we can. It helps to ensure its not used even more than
deprecating. We also don't want to remove the comments altogether, to ensure the
field isn't reused.

[sky, 2015-10-23 15:43:49]

LGTM

[maxbogue, 2015-10-23 16:36:32]

lgtm

[Nicolas Zea, 2015-10-23 18:20:49]

The CQ bit was checked by zea@chromium.org

[commit-bot: I haz the power, 2015-10-23 18:21:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1424493002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1424493002/1

[commit-bot: I haz the power, 2015-10-23 19:28:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-23 19:29:24]

Patchset 1 (id:??) landed as
https://crrev.com/2d7e84c9c92f4f93efbb55aadf70d4f532574167
Cr-Commit-Position: refs/heads/master@{#355855}