Always select best favicon bitmap
We do this by always sorting candidates by score, which should list
the best-matching sizes first.
This has two positive effects:
1. On mobile, selection of high-resolution bitmap doesn't choose
the absolute largest, but the best fit.
2. On desktop, candidates are also sorted, so exact matches are more
likely to be processed first and hence reducing the total number of
downloaded images.
BUG=704496
Review-Url: https://codereview.chromium.org/2739173002
Cr-Commit-Position: refs/heads/master@{#461096}
4 files changed
