smarter about finding the most appropriate settings file.

Before this change, I inadvertently did a [gcl try] on a chrome-internal
change (it was a trivial change and not really secret, so no harm done).
After this change, that won't be possible.

Also, change breakpad to not upload the exception that is thrown when 
the user fails to provide correct log-on credentials.

TEST=none
BUG=none


Review URL: http://codereview.chromium.org/3390013

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@61738 0039d316-1c4b-4281-b951-d872f2087c98