ipc: Add the inner class OutputElement to Channel.

ipc: Add the inner class OutputElement to Channel.

OutputElement is a wrapper around messages that are going to be written to the
underlying OS IPC mechanism. It can wrap either a Message, or a data buffer
which contains serialized attachment broker metainformation.

BUG=493414
Committed: https://crrev.com/5142dc761154a396901c5f6f1e41c5bad3664ec8
Cr-Commit-Position: refs/heads/master@{#348229}

[erikchen, 2015-08-28 20:34:36]

The CQ bit was checked by erikchen@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-28 20:35:28]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309003003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309003003/1

[commit-bot: I haz the power, 2015-08-28 20:46:28]

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

[commit-bot: I haz the power, 2015-08-28 20:46:29]

Dry run: Try jobs failed on following builders:
  ios_rel_device_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_rel_device_ni...)

[erikchen, 2015-08-28 21:06:52]

The CQ bit was checked by erikchen@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-28 21:07:07]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309003003/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309003003/20001

[erikchen, 2015-08-28 21:43:38]

The CQ bit was checked by erikchen@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-28 21:43:49]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309003003/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309003003/40001

[commit-bot: I haz the power, 2015-08-28 22:46:32]

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

[commit-bot: I haz the power, 2015-08-28 22:46:33]

Dry run: Try jobs failed on following builders:
  win_chromium_x64_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[erikchen, 2015-08-28 22:54:46]

The CQ bit was checked by erikchen@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-28 22:56:22]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309003003/60001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309003003/60001

[commit-bot: I haz the power, 2015-08-28 23:34:05]

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

[commit-bot: I haz the power, 2015-08-28 23:34:06]

Dry run: Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)
  win_chromium_x64_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[erikchen, 2015-08-29 00:23:40]

The CQ bit was checked by erikchen@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-29 00:24:16]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309003003/80001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309003003/80001

[erikchen, 2015-08-29 00:47:26]

erikchen@chromium.org changed reviewers:
+ tsepez@chromium.org

[commit-bot: I haz the power, 2015-08-29 01:10:03]

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

[commit-bot: I haz the power, 2015-08-29 01:10:03]

Dry run: Try jobs failed on following builders:
  linux_chromium_clobber_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[Tom Sepez, 2015-09-10 15:41:05]

LGTM % comments.

https://codereview.chromium.org/1309003003/diff/80001/ipc/ipc_channel.cc
File ipc/ipc_channel.cc (right):

https://codereview.chromium.org/1309003003/diff/80001/ipc/ipc_channel.cc#newc...
ipc/ipc_channel.cc:55: if (message_)
nit: I'd use the ? operator here and below, just because it all fits on one
line.  Also, do you want these in the header to aid in inlining?

https://codereview.chromium.org/1309003003/diff/80001/ipc/ipc_channel.cc#newc...
ipc/ipc_channel.cc:61: if (message_)
do you want to assert that there isn't both message and buffer_?

https://codereview.chromium.org/1309003003/diff/80001/ipc/ipc_channel.h
File ipc/ipc_channel.h (right):

https://codereview.chromium.org/1309003003/diff/80001/ipc/ipc_channel.h#newco...
ipc/ipc_channel.h:251: // Takes ownership of the buffer.
add note: buffer is free via system free, must be malloc'd

[erikchen, 2015-09-10 18:43:59]

https://codereview.chromium.org/1309003003/diff/80001/ipc/ipc_channel.cc
File ipc/ipc_channel.cc (right):

https://codereview.chromium.org/1309003003/diff/80001/ipc/ipc_channel.cc#newc...
ipc/ipc_channel.cc:55: if (message_)
On 2015/09/10 15:41:05, Tom Sepez wrote:
> nit: I'd use the ? operator here and below, just because it all fits on one
> line.  Also, do you want these in the header to aid in inlining?

I switched to the ternary operator, and moved the code into the header.

https://codereview.chromium.org/1309003003/diff/80001/ipc/ipc_channel.cc#newc...
ipc/ipc_channel.cc:61: if (message_)
On 2015/09/10 15:41:05, Tom Sepez wrote:
> do you want to assert that there isn't both message and buffer_?

Given that that assertion is enforced by the constructor, the only way for both
message and buffer_ to exist is memory corruption, which is not something I'm
inclined to add assertions for.

https://codereview.chromium.org/1309003003/diff/80001/ipc/ipc_channel.h
File ipc/ipc_channel.h (right):

https://codereview.chromium.org/1309003003/diff/80001/ipc/ipc_channel.h#newco...
ipc/ipc_channel.h:251: // Takes ownership of the buffer.
On 2015/09/10 15:41:05, Tom Sepez wrote:
> add note: buffer is free via system free, must be malloc'd

Done.

[erikchen, 2015-09-10 18:45:05]

The CQ bit was checked by erikchen@chromium.org

[erikchen, 2015-09-10 18:45:05]

The patchset sent to the CQ was uploaded after l-g-t-m from tsepez@chromium.org
Link to the patchset: https://codereview.chromium.org/1309003003/#ps120001
(title: "Rebase error.")

[commit-bot: I haz the power, 2015-09-10 18:45:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309003003/120001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309003003/120001

[commit-bot: I haz the power, 2015-09-10 18:56:51]

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

[commit-bot: I haz the power, 2015-09-10 18:56:51]

Try jobs failed on following builders:
  ios_dbg_simulator_ninja on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios_dbg_simulator...)

[erikchen, 2015-09-10 19:25:30]

The CQ bit was checked by erikchen@chromium.org

[erikchen, 2015-09-10 19:25:30]

The patchset sent to the CQ was uploaded after l-g-t-m from tsepez@chromium.org
Link to the patchset: https://codereview.chromium.org/1309003003/#ps140001
(title: "Fix typo.")

[commit-bot: I haz the power, 2015-09-10 19:25:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1309003003/140001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1309003003/140001

[commit-bot: I haz the power, 2015-09-10 21:00:26]

Committed patchset #8 (id:140001)

[commit-bot: I haz the power, 2015-09-10 21:01:08]

Patchset 8 (id:??) landed as
https://crrev.com/5142dc761154a396901c5f6f1e41c5bad3664ec8
Cr-Commit-Position: refs/heads/master@{#348229}

[commit-bot: I haz the power, 2015-09-23 12:14:02]

Patchset 8 (id:??) landed as
https://crrev.com/5142dc761154a396901c5f6f1e41c5bad3664ec8
Cr-Commit-Position: refs/heads/master@{#348229}