Fix the documentation for MinidumpFileWriter::Open().

BUG=581
R=mark@chromium.org

Review URL: https://breakpad.appspot.com/6654002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1328 4c0a9323-5329-0410-9bdc-e9ce6186880e
[Mac] Remove unused host_info call and supporting calls.

R=blundell@chromium.org

Review URL: https://breakpad.appspot.com/2684002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1329 4c0a9323-5329-0410-9bdc-e9ce6186880e