Disable support for the Mac NPAPI Carbon event model

Disable support for the Mac NPAPI Carbon event model

Abort any plugin that doesn't negotiate the Cocoa event model, except
for the Chromium test plugin. Once the test plugin is updated to Cocoa,
Carbon event model support will be removed entirely.

BUG=125915
TEST=All the well-known Mac NPAPI plugins that worked before should still work.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=149642

[stuartmorgan, 2012-08-02 08:02:54]

To Mark first for product sign-off.

Two part explanation:
1) The motivation to drop Carbon support is that I'm not aware of any plugin
that currently works in Chrome (since QD was dropped) that uses Carbon. The only
potential downside I see is that a plugin that's QD+Carbon *could* go CG+Carbon,
but realistically the plugins I know of that use QD would almost certainly go
directly to CA (which requires Cocoa). Dropping Carbon lets us get rid of a
bunch of hacky code to get things working OOP, and is a big step toward dropping
the hated interpose library.

2) The reason for this weird disable-it-but-keep-the-code CL is that I don't
have the bandwidth to update our test plugin to Cocoa before M22 is cut (there
were run loop issues in the contexts of tests that I haven't investigated yet),
but I really want Carbon not to work in M22. There is a long tail of niche
plugins (mostly extension helpers) that don't do any drawing or event handling,
and thus never bothered to do model negotiation; those plugins will all break in
M22 until (trivially) updated. I've gotten bugs/emails about 3 so far, and in
every case I've told them to update to CG+Cocoa. However, there are doubtless
others I haven't heard about, and who will figure it out on their own. What I
want to avoid is them figuring out they need to go to CG+Carbon to work in M22,
and then immediately be broken again in M23 when I should have time to rip
Carbon out entirely. By disabling it now, the bustage is confined to one release
and plugin authors will update to CG+Cocoa all at once.

[Mark Mentovai, 2012-08-02 14:32:17]

LGTM. Now’s a good time to try dropping this, and this is a good way to do it.
If the feedback shows that it was premature to drop (and it likely won’t), it’ll
be easy to turn back on, even on the branch.

[stuartmorgan, 2012-08-02 15:00:23]

+bauerb for OWNERS

[Bernhard Bauer, 2012-08-02 15:19:51]

lgtm

[commit-bot: I haz the power, 2012-08-02 15:29:58]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/stuartmorgan@chromium.org/10823138/3001

[commit-bot: I haz the power, 2012-08-02 17:09:56]

Change committed as 149642