Also remove Library/Safari from users home dir if --clear_safari_cache is set
Also remove Library/Safari from users home dir if --clear_safari_cache is set

Additionally, actually handle errors on deletion correctly by checking for existense first and actually failing if we fail to delete the directory.

R=kustermann@google.com

Review URL: https://codereview.chromium.org//17450017

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@24238 260f80e4-7a28-3924-810f-c04153c831b5

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