Hook prerender into non-CURRENT_TAB dispositions.

Hook prerender into non-CURRENT_TAB dispositions.

SwapInternal checks if CoreTabHelper::delegate is NULL now, and a
non-CURRENT_TAB disposition would require the asynchronous codepath anyway, so
it's fine that the WebContents is still to be attached.

BUG=345474
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=270278

[davidben, 2014-04-30 16:54:05]

This turned out to be pretty easy. And it seems middle-clicking makes a new
BrowsingInstance now, so it ends up being useful too.

[tburkard, 2014-05-06 18:50:10]

lgtm

[sky, 2014-05-07 21:38:26]

LGTM

[davidben, 2014-05-07 21:41:00]

The CQ bit was checked by davidben@chromium.org

[commit-bot: I haz the power, 2014-05-07 21:42:41]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/davidben@chromium.org/261623004/1

[commit-bot: I haz the power, 2014-05-07 23:09:38]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  android_dbg_triggered_tests on tryserver.chromium

[davidben, 2014-05-07 23:28:07]

On 2014/05/07 23:09:38, I haz the power (commit-bot) wrote:
> FYI, CQ is re-trying this CL (attempt #1).
> Please consider checking whether the failures are real,
> and report flakes to mailto:chrome-troopers@google.com.
> The failing builders are:
>   android_dbg_triggered_tests on tryserver.chromium

Unchecking CQ bit; Android unlikely to be related, but let's hold on this until
after branch point anyway.

[davidben, 2014-05-07 23:28:09]

The CQ bit was unchecked by davidben@chromium.org

[davidben, 2014-05-13 21:56:50]

The CQ bit was checked by davidben@chromium.org

[commit-bot: I haz the power, 2014-05-13 22:04:48]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/davidben@chromium.org/261623004/1

[commit-bot: I haz the power, 2014-05-13 23:41:59]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  android_dbg_triggered_tests on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/android_dbg_triggered...)

[commit-bot: I haz the power, 2014-05-14 01:09:25]

Change committed as 270278