I found the same error as described in a bug with our test accounts. And
I suppose this problem can be as result not correct import autocomplete
entries from the other browsers. For example the import from the firefox
browser doesn't validate name and value fields in autofill entry before
writing it in an autofill table so the browser can import not valid entry
from other browser.
Also the browser doesn't need to cut null terminating symbol in a name
or a value, because the browser generates differ tag for autocomplete
entry and lose link between autocomplete table and local synchronization
database entries.

BUG=596170

Review-Url: https://codereview.chromium.org/2646783002
Cr-Commit-Position: refs/heads/master@{#445348}