Do Keychain reauthorization at update time

Do Keychain reauthorization at update time.

In addition to the at-launch reauthorization, this adds an at-update
reauthorization step. It only runs for users not on a system Keystone ticket,
because the updater runs as root when on a system ticket, and root can't read
individual user's Keychains. The at-update reauthorization is intended to
handle the reauthorization for users who rarely restart Chrome and might miss
out on the at-launch step during the window where Chrome is signed by the old
certificate but has the new reauthorization code in place. The at-update
reauthorization step can remain in place even after the certificate switch
occurs by shipping an old reauthorization stub binary signed with the old
certificate.

BUG=108238
TEST=none
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=137501

[TVL, 2012-05-16 20:05:10]

lgtm

https://chromiumcodereview.appspot.com/10377173/diff/1/chrome/browser/chrome_...
File chrome/browser/chrome_browser_main_mac.mm (right):

https://chromiumcodereview.appspot.com/10377173/diff/1/chrome/browser/chrome_...
chrome/browser/chrome_browser_main_mac.mm:74:
@"KeychainReauthorizeAtUpdateMay2012";
comment on when this key should be updated/changed?

https://chromiumcodereview.appspot.com/10377173/diff/1/chrome/browser/chrome_...
chrome/browser/chrome_browser_main_mac.mm:169:
@"KeychainReauthorizeInAppMay2012";
same comment.  Might even make sense to move the constants up to the top of the
file to comment on how they differ?

[Mark Mentovai, 2012-05-16 20:24:52]

Addressed!