Merge trunk r140081 to the 19.0.1084 branch.

Merge trunk r140081 to the 19.0.1084 branch.

Only reauthorize passwords. Don't try to reauthorize private keys, because
they were getting deleted instead of reauthorized.

BUG=130738
TEST=Put a private key in your Keychain, give Chrome access, and run through
     the reauthorization workflow. The private key should not be touched by
     reauthorization. You can ensure you get the reauthorization workflow by
     running:
     $ defaults delete com.google.Chrome KeychainReauthorizeInAppMay2012
     $ defaults delete com.google.Chrome KeychainReauthorizeInAppMay2012Success
     and launching a copy of Chrome with this change present.

     To get a private key in your Keychain, open
     /Applications/Utilities/Keychain Access.app and choose Certificate
     Assistant/Create a Certificate from the Keychain Access menu. For this
     test, it's OK to accept the defaults. Find the private key added to your
     Keychain, select it and press command-I for Get Info, switch to the
     Access Control tab, and add Chrome to the list of applications allowed
     access to the private key.
Review URL: https://chromiumcodereview.appspot.com/10466005
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=140248