Keep going with Vista default browser registration if there is a failure.
Keep going with Vista default browser registration if there is a failure.

Keep going if there is a failure as rolling back is complicated and relies
on undocumented Windows behaviour. Log any problems and return false from
registration function.

BUG=90372
TEST=Manual testing performed


Review URL: http://codereview.chromium.org/7491039

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@94034 0039d316-1c4b-4281-b951-d872f2087c98

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