Add LOAD_PREFETCH flag for all requests sent by resource prefetcher

Add LOAD_PREFETCH flag for all requests sent by resource prefetcher

1. This allows other constraints about prefetched resources to be applied.
2. Together with another CL https://codereview.chromium.org/793823002/, the prefetched resources can temporarily bypass revalidation.

BUG=405690, 406209
Committed: https://crrev.com/42c496ddef40221858df3df41dc7ef8105a82af3
Cr-Commit-Position: refs/heads/master@{#315369}

[Zhen Wang, 2015-02-02 22:44:38]

zhenw@chromium.org changed reviewers:
+ cbentzel@chromium.org

[Zhen Wang, 2015-02-04 15:06:49]

Hi Chris, can you take a look? Or do you know who is the best to review this?

[cbentzel, 2015-02-09 13:24:03]

LGTM

Sorry for delay

[Zhen Wang, 2015-02-09 16:31:02]

The CQ bit was checked by zhenw@chromium.org

[commit-bot: I haz the power, 2015-02-09 16:32:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/891343007/1

[commit-bot: I haz the power, 2015-02-09 16:38:18]

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

[commit-bot: I haz the power, 2015-02-09 16:38:19]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[Zhen Wang, 2015-02-09 20:00:03]

zhenw@chromium.org changed reviewers:
+ thestig@chromium.org

[Zhen Wang, 2015-02-09 20:00:03]

Hi Lei, can you take a look since you reviewed related CLs before? Thanks!

[Lei Zhang, 2015-02-09 20:07:40]

lgtm

[Zhen Wang, 2015-02-09 20:09:12]

The CQ bit was checked by zhenw@chromium.org

[commit-bot: I haz the power, 2015-02-09 20:09:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/891343007/1

[commit-bot: I haz the power, 2015-02-09 20:13:34]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-09 20:13:59]

Patchset 1 (id:??) landed as
https://crrev.com/42c496ddef40221858df3df41dc7ef8105a82af3
Cr-Commit-Position: refs/heads/master@{#315369}