Re-land: [mojo-edk] Serialise windows handles into an "extra header" section.

Re-land: [mojo-edk] Serialise windows handles into an "extra header" section.

This change introduces an "extra header" section of a channel message
header. On windows, platform handles are place into this section instead
of being appended to the end of a message.

At the same time, make a couple of smaller changes:
1. Allow the number of serialised handles to be less than the number
stated in the constructor.
2. Add a has_mach_ports() helper function.
3. Limit the number of attached handles.

These changes are all prep work for Mach ports support.

This re-land perserves the old wire format and message semantics on ChromeOS
and changes it on all other platforms.

Original change: https://codereview.chromium.org/1740953002

BUG=582468
Committed: https://crrev.com/ebaca1a5f5909b5cacbb3ebebbacb1968486cd16
Cr-Commit-Position: refs/heads/master@{#379114}

[Anand Mistry (off Chromium), 2016-03-03 02:29:26]

amistry@chromium.org changed reviewers:
+ rockot@chromium.org

[Ken Rockot(use gerrit already), 2016-03-03 02:34:44]

rockot@chromium.org changed reviewers:
+ elijahtaylor@chromium.org

[Ken Rockot(use gerrit already), 2016-03-03 02:34:45]

Thanks for doing this, one comment

https://codereview.chromium.org/1759033002/diff/1/mojo/edk/system/channel.h
File mojo/edk/system/channel.h (right):

https://codereview.chromium.org/1759033002/diff/1/mojo/edk/system/channel.h#n...
mojo/edk/system/channel.h:48: #if defined(OS_CHROMEOS)
I think we need to verify that this is a sufficient check. I don't know what
kind of build is running on the Android side. Maybe we need old header format
for OS_CHROMEOS and OS_ANDROID? +elijahtaylor

[Anand Mistry (off Chromium), 2016-03-03 02:36:55]

https://codereview.chromium.org/1759033002/diff/1/mojo/edk/system/channel.h
File mojo/edk/system/channel.h (right):

https://codereview.chromium.org/1759033002/diff/1/mojo/edk/system/channel.h#n...
mojo/edk/system/channel.h:48: #if defined(OS_CHROMEOS)
On 2016/03/03 02:34:45, Ken Rockot wrote:
> I think we need to verify that this is a sufficient check. I don't know what
> kind of build is running on the Android side. Maybe we need old header format
> for OS_CHROMEOS and OS_ANDROID? +elijahtaylor

I had the same thought, so I've commented on the internal bug.

[elijahtaylor1, 2016-03-03 18:33:46]

https://codereview.chromium.org/1759033002/diff/1/mojo/edk/system/channel.h
File mojo/edk/system/channel.h (right):

https://codereview.chromium.org/1759033002/diff/1/mojo/edk/system/channel.h#n...
mojo/edk/system/channel.h:48: #if defined(OS_CHROMEOS)
On 2016/03/03 02:36:55, Anand Mistry wrote:
> On 2016/03/03 02:34:45, Ken Rockot wrote:
> > I think we need to verify that this is a sufficient check. I don't know what
> > kind of build is running on the Android side. Maybe we need old header
format
> > for OS_CHROMEOS and OS_ANDROID? +elijahtaylor
> 
> I had the same thought, so I've commented on the internal bug.

If this was the question, ARC only builds Chrome for OS_CHROMEOS

[Ken Rockot(use gerrit already), 2016-03-03 18:38:18]

Thanks for the confirmation. In that case, LGTM

[Anand Mistry (off Chromium), 2016-03-03 22:05:34]

The CQ bit was checked by amistry@chromium.org

[commit-bot: I haz the power, 2016-03-03 22:05:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1759033002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1759033002/1

[commit-bot: I haz the power, 2016-03-03 22:25:36]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-03-03 22:27:46]

Description was changed from

==========
Re-land: [mojo-edk] Serialise windows handles into an "extra header" section.

This change introduces an "extra header" section of a channel message
header. On windows, platform handles are place into this section instead
of being appended to the end of a message.

At the same time, make a couple of smaller changes:
1. Allow the number of serialised handles to be less than the number
stated in the constructor.
2. Add a has_mach_ports() helper function.
3. Limit the number of attached handles.

These changes are all prep work for Mach ports support.

This re-land perserves the old wire format and message semantics on ChromeOS
and changes it on all other platforms.

Original change: https://codereview.chromium.org/1740953002

BUG=582468
==========

to

==========
Re-land: [mojo-edk] Serialise windows handles into an "extra header" section.

This change introduces an "extra header" section of a channel message
header. On windows, platform handles are place into this section instead
of being appended to the end of a message.

At the same time, make a couple of smaller changes:
1. Allow the number of serialised handles to be less than the number
stated in the constructor.
2. Add a has_mach_ports() helper function.
3. Limit the number of attached handles.

These changes are all prep work for Mach ports support.

This re-land perserves the old wire format and message semantics on ChromeOS
and changes it on all other platforms.

Original change: https://codereview.chromium.org/1740953002

BUG=582468

Committed: https://crrev.com/ebaca1a5f5909b5cacbb3ebebbacb1968486cd16
Cr-Commit-Position: refs/heads/master@{#379114}
==========

[commit-bot: I haz the power, 2016-03-03 22:27:47]

Patchset 1 (id:??) landed as
https://crrev.com/ebaca1a5f5909b5cacbb3ebebbacb1968486cd16
Cr-Commit-Position: refs/heads/master@{#379114}