Document SkString::resize(int) as destructive.

It is easy to think in some cases that SkString::resize(int) is not
destructive, since optimizations mean that most of the time the data
is still there after a resize. However, in the general case, the
original string's data is lost and the new SkString contains garbage.

Review URL: https://codereview.chromium.org/1304833004
1 file changed