Referrer Policy: Distinguish "default" from "no referrer when downgrade" [2/2]

Referrer Policy: Distinguish "default" from "no referrer when downgrade" [2/2]

We can drop a boolean from Document by adding a value to the ReferrerPolicy
enum to distinguish "default" from an explicitly-set "no referrer when
downgrade".

This patch also marginally increases the detail of the metrics we're
gathering ReferrerPolicy resets.

[1/2] Chromium: https://codereview.chromium.org/717503002/
[2/2] Blink: This patch.

BUG=431694
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=185041

[Mike West, 2014-11-10 12:13:33]

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

[Mike West, 2014-11-10 12:13:33]

Ditto.

[jochen (gone - plz use gerrit), 2014-11-10 13:39:48]

lgtm

[Mike West, 2014-11-10 15:06:36]

The CQ bit was checked by mkwst@chromium.org

[commit-bot: I haz the power, 2014-11-10 15:07:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/698973008/1

[commit-bot: I haz the power, 2014-11-10 16:12:06]

Committed patchset #1 (id:1) as 185041

[rohitrao (ping after 24h), 2015-01-28 23:56:56]

We serialize this enum to disk (through SerializedNavigationEntry), which means
that adding a new value to the middle of this enum will probably cause issues? 
I believe that anyone running a build after this change will load an incorrect
referrer policy when reading tabs from disk.

[jochen (gone - plz use gerrit), 2015-01-29 08:56:05]

On 2015/01/28 at 23:56:56, rohitrao wrote:
> We serialize this enum to disk (through SerializedNavigationEntry), which
means that adding a new value to the middle of this enum will probably cause
issues?  I believe that anyone running a build after this change will load an
incorrect referrer policy when reading tabs from disk.

ouch, good catch!