PPAPI: Move PPB_Messaging 1.2 to stable

PPAPI: Move PPB_Messaging 1.2 to stable

This adds postMessageAndAwaitResponse() support to Pepper stable.

Open issues:
1) This is arguably an expansion on what JavaScript can do today. In particular,
it would be possible to make JavaScript block on PNaCl, which blocks on another
thread, which blocks on something like synchronous FileIO.
2) Not all types are supported yet; e.g. FileRef and FileSystem. I want to fix
that prior to M39. (see https://code.google.com/p/chromium/codesearch#chromium/src/content/renderer/pepper/message_channel.cc&l=305)

BUG=367896
Committed: https://crrev.com/9be4c268e89e2a759a670d55769defbd29bdd224
Cr-Commit-Position: refs/heads/master@{#297026}

[dmichael (off chromium), 2014-09-26 18:37:41]

dmichael@chromium.org changed reviewers:
+ bbudge@chromium.org

[teravest, 2014-09-26 20:03:54]

teravest@chromium.org changed reviewers:
+ teravest@chromium.org

[teravest, 2014-09-26 20:03:54]

lgtm

[dmichael (off chromium), 2014-09-26 20:12:53]

The CQ bit was checked by dmichael@chromium.org

[commit-bot: I haz the power, 2014-09-26 20:13:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/600893002/80001

[bbudge, 2014-09-26 20:20:04]

lgtm

[commit-bot: I haz the power, 2014-09-26 20:39:39]

Committed patchset #5 (id:80001) as 234479ec0a4383dc919b144f5fd2bc94c0e8d458

[commit-bot: I haz the power, 2014-09-26 20:40:20]

Patchset 5 (id:??) landed as
https://crrev.com/9be4c268e89e2a759a670d55769defbd29bdd224
Cr-Commit-Position: refs/heads/master@{#297026}

[Junichi Uekawa, 2014-10-10 00:55:59]

uekawa@chromium.org changed reviewers:
+ uekawa@chromium.org

[Junichi Uekawa, 2014-10-10 00:56:01]

https://codereview.chromium.org/600893002/diff/80001/ppapi/c/ppb_messaging.h
File ppapi/c/ppb_messaging.h (right):

https://codereview.chromium.org/600893002/diff/80001/ppapi/c/ppb_messaging.h#...
ppapi/c/ppb_messaging.h:21: #define PPB_MESSAGING_INTERFACE
PPB_MESSAGING_INTERFACE_1_2
This makes an interface which was available since Sep 17 to stable, so any code
that gets compiled against this is going to fail running on stable chrome
(get_interface returns 0).

I think this is a problem, but how is this usually done?

[Junichi Uekawa, 2014-10-10 03:50:44]

https://codereview.chromium.org/600893002/diff/80001/ppapi/c/ppb_messaging.h
File ppapi/c/ppb_messaging.h (right):

https://codereview.chromium.org/600893002/diff/80001/ppapi/c/ppb_messaging.h#...
ppapi/c/ppb_messaging.h:21: #define PPB_MESSAGING_INTERFACE
PPB_MESSAGING_INTERFACE_1_2
On 2014/10/10 00:56:00, Junichi Uekawa wrote:
> This makes an interface which was available since Sep 17 to stable, so any
code
> that gets compiled against this is going to fail running on stable chrome
> (get_interface returns 0).
> 
> I think this is a problem, but how is this usually done?

nevermind, my understanding now is that code compiled against this canary ppapi
will only work on canary chrome, and not with older chrome versions.