HttpServerProperties - Don't persist if SetSupportsSpdy is called with

HttpServerProperties - Don't persist if SetSupportsSpdy is called with
the same origin (HostPortPair) and value (supports_spdy).

This change reduces the number of times SetSupportsSpdy tries to persist
HttpServerProperties to disk (currently ~5% of persist calls are due to
SetSupportsSpdy).

BUG=451256
R=rch@chromium.org

Committed: https://crrev.com/e267d6a5e8f7fd198c4ac5d11d7098a1d17228c5
Cr-Commit-Position: refs/heads/master@{#333146}

[ramant (doing other things), 2015-05-29 00:20:11]

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

[commit-bot: I haz the power, 2015-05-29 00:20:29]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1159853005/1

[commit-bot: I haz the power, 2015-05-29 00:26:01]

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

[commit-bot: I haz the power, 2015-05-29 00:26:02]

Dry run: This issue passed the CQ dry run.

[ramant (doing other things), 2015-05-29 00:30:59]

Hi Ryan,
  This is similar to other HttpServerProperties changes. Made the change for
"SupportsSpdy".

thanks
raman

[ramant (doing other things), 2015-06-05 16:55:33]

On 2015/05/29 00:30:59, ramant wrote:
> Hi Ryan,
>   This is similar to other HttpServerProperties changes. Made the change for
> "SupportsSpdy".
> 
> thanks
> raman

Hi Ryan,
  Would appreciate if you could take a look.
thanks
raman

[ramant (doing other things), 2015-06-05 16:56:14]

PTAL.

thanks
raman

[Ryan Hamilton, 2015-06-05 20:32:16]

lgtm

[ramant (doing other things), 2015-06-05 21:47:45]

The CQ bit was checked by rtenneti@chromium.org

[commit-bot: I haz the power, 2015-06-05 21:49:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1159853005/20001

[commit-bot: I haz the power, 2015-06-05 21:55:30]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-06-05 21:56:31]

Patchset 2 (id:??) landed as
https://crrev.com/e267d6a5e8f7fd198c4ac5d11d7098a1d17228c5
Cr-Commit-Position: refs/heads/master@{#333146}