For types that support Pass(), e.g. scoped_ptr and friends, use Passed in PostTaskAndReplyWithResul…

When using PostTaskAndReplyWithResults, if the ResultType is a passed type (eg: scoped_ptr and friends), .Pass() the result to the reply.

Because the temporary storage of the result is an implementation detail of PostTaskAndReplyWithResults, its safe to always assume that passed types should be passed.

BUG=126008
TEST=TaskRunnerHelpersTest.PostTaskAndReplyWithResultPassed


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=135228

[Ryan Sleevi, 2012-05-03 00:35:20]

I really wanted to use this... so... template foo.

[Ryan Sleevi, 2012-05-03 00:45:25]

Err, I completely missed the existence of CallbackForward. Please let me know if
it's too hacky to depend on callback_internal, but it seems to work.

I can move the SFINAE checking of .Pass() into callback_internal, to avoid the
whitelist, if that's a sticking point.

[willchan no longer on Chromium, 2012-05-03 03:28:44]

LGTM, I think your use of CallbackForward() is fine. Please add a comment noting
this tight coupling of task_runner_util.h to CallbackForward(), and saying it'd
be nice to remove it in C++11.

http://codereview.chromium.org/10344012/diff/3001/base/task_runner_util_unitt...
File base/task_runner_util_unittest.cc (right):

http://codereview.chromium.org/10344012/diff/3001/base/task_runner_util_unitt...
base/task_runner_util_unittest.cc:72: EXPECT_EQ(g_foo_destruct_count, 1);
(expected, actual)

[commit-bot: I haz the power, 2012-05-03 19:19:17]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/rsleevi@chromium.org/10344012/10004

[commit-bot: I haz the power, 2012-05-03 22:34:20]

Change committed as 135228