Add support for multiple zygote fork delegates

Add support for multiple zygote fork delegates

No functional changes yet, just preparation for splitting NaCl's fork
delegate into two different implementations.

BUG=364945
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=269673

[mdempsky, 2014-05-09 03:40:55]

Mostly just a matter of changing ZygoteForkDelegate* to
ScopedVector<ZygoteForkDelegate> in a bunch of APIs; the only really interesting
changes (IMO) are in content/zygote.

[jln (very slow on Chromium), 2014-05-09 20:42:37]

lgtm, as discussed in person this is a good starting point for fixing the
linked-bug.

[mdempsky, 2014-05-09 21:08:59]

piman: Please review changes to content/app and content/common for OWNERS
approval.

cpu: Please review tiny changes to chrome/app for OWNERS approval.

These changes don't alter behavior at all for now, they just make it possible
for NaCl to use multiple zygote fork delegates in the future.  In particular,
they just change APIs that currently allow a single ZygoteForkDelegate* to
instead use a ScopedVector<ZygoteForkDelegate>.

[mdempsky, 2014-05-09 21:10:52]

On 2014/05/09 21:08:59, mdempsky wrote:
> piman: Please review changes to content/app and content/common for OWNERS
> approval.

Sorry, that should be "content/app and content/*public*"!  (I.e., the content/
directories other than content/zygote, though of course feedback is welcome
there too. :))

> cpu: Please review tiny changes to chrome/app for OWNERS approval.
> 
> These changes don't alter behavior at all for now, they just make it possible
> for NaCl to use multiple zygote fork delegates in the future.  In particular,
> they just change APIs that currently allow a single ZygoteForkDelegate* to
> instead use a ScopedVector<ZygoteForkDelegate>.

[piman, 2014-05-09 21:58:23]

lgtm

[cpu_(ooo_6.6-7.5), 2014-05-10 00:15:28]

rs lgtm

[mdempsky, 2014-05-10 01:00:06]

The CQ bit was checked by mdempsky@chromium.org

[commit-bot: I haz the power, 2014-05-10 01:04:20]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mdempsky@chromium.org/269413004/20001

[commit-bot: I haz the power, 2014-05-10 03:32:28]

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:
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)

[commit-bot: I haz the power, 2014-05-10 03:38:31]

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

[commit-bot: I haz the power, 2014-05-10 03:38:32]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)

[mdempsky, 2014-05-10 05:22:57]

The CQ bit was checked by mdempsky@chromium.org

[commit-bot: I haz the power, 2014-05-10 05:24:14]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mdempsky@chromium.org/269413004/20001

[commit-bot: I haz the power, 2014-05-10 05:29:51]

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:
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)

[commit-bot: I haz the power, 2014-05-10 05:33:27]

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

[commit-bot: I haz the power, 2014-05-10 05:33:27]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium
(http://build.chromium.org/p/tryserver.chromium/builders/chromium_presubmit/bu...)

[mdempsky, 2014-05-10 06:39:35]

The CQ bit was checked by mdempsky@chromium.org

[commit-bot: I haz the power, 2014-05-10 06:43:20]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mdempsky@chromium.org/269413004/20001

[commit-bot: I haz the power, 2014-05-11 01:17:49]

Change committed as 269673