POSIX: read subprocess output before waiting for termination.
POSIX: read subprocess output before waiting for termination.

Previously, GetAppOutput was designed only for fuser. However, it
appears that Mac is using it to read the output of ps: which outputs
rather more. In this case, ps can fill up the pipe buffer while we are
waiting for it to exit, leading to deadlock depending on how many other
process are running on the system at the time.

http://codereview.chromium.org/118514


git-svn-id: http://src.chromium.org/svn/trunk/src@18068 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 69dd568bd10aece3ad1b0e22acfee90d59171456
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser