[Mac] address perf regressions on bots
[Mac] address perf regressions on bots

This isn't the prettiest, but it should get the perf back where we want it.  If the file we're asked to exclude is in /var or /private, ignore it.  The problem on the bots is the TimeMachine prefs plist is growing unbounded as we keep adding 4 files each run for temporary profiles.  The load/modify/write gets slower with each addition.  This quick/dirty check to avoid that.  Since the original bug for the backup of this data is still open, I figure landing this is the right thing to do until that is fully addressed.

BUG=25959,30002
TEST=page cycles, browser_tests all get back to being fast.  normal profiles still exclude the files listed in the first bug.
Review URL: http://codereview.chromium.org/523024

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@35382 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser