The main API change IgnoreResult() and fully currying. See unittest for what the new API looks like. The rest of the changes are done to support that.
Previously, IgnoreReturn could not be used with WeakPtr<> Bind()s as it was applied after the fact to the Callback object. Now, IgnoreResult() wraps the function like Unretained().
As an incidental benefit, the new implementation gave us fully currying for free.
Also, the new implementation scales better when supporting higher arities of functions. The new type growth is:
(n^2 + 20n) / 2
as opposed to
(3n^2 + 17n) / 2
where n == arity.
For n = 6 and n=10, the new implementation has 81 and 155 templates respectively.
The old implementation had 105 and 235 templates respectively.
BUG=35233,98919,98542
TEST=existing unittests
Review URL: http://codereview.chromium.org/8483003
git-svn-id: http://src.chromium.org/svn/trunk/src/build@110975 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
ajwong@chromium.org