Mac: Deflake AppListServiceInteractiveTest.SwitchAppListProfilesDuringSearch

Mac: Deflake AppListServiceInteractiveTest.SwitchAppListProfilesDuringSearch

This is flaky because the app list ends up trying to read an ImageSkia
on one of Cocoa's background threads.

While NSView has a `canDrawConcurrently` function, AppKit is not calling
it in the case that is making this test flaky. The documentation says,
"The default is NO for most types of views.." [sic], and I've verified
it is `NO` and tried overriding it, but it was just never called.

However, having -[NSView canDraw] return `NO` seems to work fine.
Returning NO when there is no message loop ensures a draw only occurs on
a thread that Chrome created (not one of Cocoa's background threads),
and doesn't raise any DEPS issues.

BUG=417148, 415264
Committed: https://crrev.com/9a068829483acbd5290eedbdc8102d92b98ffab8
Cr-Commit-Position: refs/heads/master@{#296591}

[tapted, 2014-09-24 08:07:01]

tapted@chromium.org changed reviewers:
+ jackhou@chromium.org

[tapted, 2014-09-24 08:12:16]

OK last one (phew!). I think this one was always flaky, just it's quite rare so
would almost always succeed on a retry.

Thanks Jack!

[jackhou1, 2014-09-24 09:23:27]

lgtm

[tapted, 2014-09-25 00:09:25]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2014-09-25 00:10:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/599803002/60001

[commit-bot: I haz the power, 2014-09-25 00:33:00]

Committed patchset #4 (id:60001) as e7b4da7601bd98ea0c5a5eb05c206fcd23fa7a68

[commit-bot: I haz the power, 2014-09-25 00:33:38]

Patchset 4 (id:??) landed as
https://crrev.com/9a068829483acbd5290eedbdc8102d92b98ffab8
Cr-Commit-Position: refs/heads/master@{#296591}