Return response in Hangouts services extension stopAndUpload as soon as an error occurs.
Return response in Hangouts services extension stopAndUpload as soon as an error occurs.

This makes it easier to see exactly what failed.

Review URL: https://codereview.chromium.org/1295123002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#344514}

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