GitLab

- Was loading thumbnails in little endian, but since the files were from java's
output stream they were in big endian.  This was causing all sorts of issues
with old thumbnails.
- Added back ETC1 header and fixed the file format to match the old version.

BUG=398319

Review URL: https://codereview.chromium.org/486093002

Cr-Commit-Position: refs/heads/master@{#290708}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@290708 0039d316-1c4b-4281-b951-d872f2087c98