IPC: Add MojoHandleAttachment

IPC: Add MojoHandleAttachment

This CL introduces MojoHandleAttachment, a MessageAttachment subclass.
With this and ChannelMojo, we are able to send Mojo MessagePipes
over IPC.

There is also MojoMessageHelper which provides some static member functions
that reads and writes MessagePipes from/to a Message. In coming changes,
we'll add ParamTraits for MessagePipe based on this.

R=agl@chromium.org, viettrungluu@chromium.org
TEST=IPCChannelMojoTest.SendMessagePipe, IPCChannelMojoTest.SendPlatformHandleAndPipe
BUG=448190
Committed: https://crrev.com/81b17e069328d70e1008c958251ff1ddfed5b4f8
Cr-Commit-Position: refs/heads/master@{#314930}

[Hajime Morrita, 2015-02-03 23:12:22]

agl: PTAL at ipc/* ? It's a minor change.
Trung: PTAL at ipc/mojo ?

[Hajime Morrita, 2015-02-03 23:34:21]

The description was broken. It should be "IPC: Add MojoHandleAttachment".
Corrected.

[agl, 2015-02-04 00:17:47]

https://codereview.chromium.org/866223005/diff/20001/ipc/ipc_message.cc
File ipc/ipc_message.cc (right):

https://codereview.chromium.org/866223005/diff/20001/ipc/ipc_message.cc#newco...
ipc/ipc_message.cc:159: return attachment_set_.get() &&
attachment_set_->num_mojo_handles();
Feel free to ignore: put "> 0" on the end to avoid the subtle cast from size_t
to bool?

https://codereview.chromium.org/866223005/diff/20001/ipc/ipc_message.h
File ipc/ipc_message.h (right):

https://codereview.chromium.org/866223005/diff/20001/ipc/ipc_message.h#newcod...
ipc/ipc_message.h:178: // Returns true if there are any MojoHandleAttachment in
this message.
s on the end of "MojoHandleAttachment"?

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
File ipc/mojo/ipc_channel_mojo.cc (right):

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
ipc/mojo/ipc_channel_mojo.cc:386: NOTREACHED();
I think the indentation of this line is wrong.

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
ipc/mojo/ipc_channel_mojo.cc:389: case MessageAttachment::TYPE_MOJO_HANDLE: {
blank line before this.

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
ipc/mojo/ipc_channel_mojo.cc:412: DCHECK(ok);
if (!ok) {
  return <some error value>
}

?

[Hajime Morrita, 2015-02-04 00:44:51]

PTAL?

https://codereview.chromium.org/866223005/diff/20001/ipc/ipc_message.cc
File ipc/ipc_message.cc (right):

https://codereview.chromium.org/866223005/diff/20001/ipc/ipc_message.cc#newco...
ipc/ipc_message.cc:159: return attachment_set_.get() &&
attachment_set_->num_mojo_handles();
On 2015/02/04 00:17:46, agl wrote:
> Feel free to ignore: put "> 0" on the end to avoid the subtle cast from size_t
> to bool?
Done. That's clearer anyway.

https://codereview.chromium.org/866223005/diff/20001/ipc/ipc_message.h
File ipc/ipc_message.h (right):

https://codereview.chromium.org/866223005/diff/20001/ipc/ipc_message.h#newcod...
ipc/ipc_message.h:178: // Returns true if there are any MojoHandleAttachment in
this message.
On 2015/02/04 00:17:46, agl wrote:
> s on the end of "MojoHandleAttachment"?

Done.

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
File ipc/mojo/ipc_channel_mojo.cc (right):

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
ipc/mojo/ipc_channel_mojo.cc:386: NOTREACHED();
On 2015/02/04 00:17:47, agl wrote:
> I think the indentation of this line is wrong.

Done.

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
ipc/mojo/ipc_channel_mojo.cc:389: case MessageAttachment::TYPE_MOJO_HANDLE: {
On 2015/02/04 00:17:46, agl wrote:
> blank line before this.

Done.

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
ipc/mojo/ipc_channel_mojo.cc:412: DCHECK(ok);
On 2015/02/04 00:17:46, agl wrote:
> if (!ok) {
>   return <some error value>
> }
> 
> ?
There is no upper bound of mojo handles.
Might be good to have the error check just in case though.
Done.

[agl, 2015-02-04 00:49:06]

lgtm

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
File ipc/mojo/ipc_channel_mojo.cc (right):

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
ipc/mojo/ipc_channel_mojo.cc:389: case MessageAttachment::TYPE_MOJO_HANDLE: {
On 2015/02/04 00:44:51, morrita wrote:
> On 2015/02/04 00:17:46, agl wrote:
> > blank line before this.
> 
> Done.

Not clear from codereview that this happened.

[Hajime Morrita, 2015-02-04 01:11:44]

New patchsets have been uploaded after l-g-t-m from agl@chromium.org

[Hajime Morrita, 2015-02-05 00:42:06]

Thanks!
Trung: Ping?

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
File ipc/mojo/ipc_channel_mojo.cc (right):

https://codereview.chromium.org/866223005/diff/20001/ipc/mojo/ipc_channel_moj...
ipc/mojo/ipc_channel_mojo.cc:389: case MessageAttachment::TYPE_MOJO_HANDLE: {
On 2015/02/04 00:49:06, agl wrote:
> On 2015/02/04 00:44:51, morrita wrote:
> > On 2015/02/04 00:17:46, agl wrote:
> > > blank line before this.
> > 
> > Done.
> 
> Not clear from codereview that this happened.
Hmm. I guess The tool shows you an older revision?

[Hajime Morrita, 2015-02-06 00:20:21]

The CQ bit was checked by morrita@chromium.org

[commit-bot: I haz the power, 2015-02-06 00:21:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/866223005/80001

[commit-bot: I haz the power, 2015-02-06 00:59:07]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2015-02-06 00:59:59]

Patchset 5 (id:??) landed as
https://crrev.com/81b17e069328d70e1008c958251ff1ddfed5b4f8
Cr-Commit-Position: refs/heads/master@{#314930}