Translate Account locale to device locale asynchronously through WorkerPool.

BUG=297885

TEST=manual

Review URL: https://codereview.chromium.org/24753002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228038 0039d316-1c4b-4281-b951-d872f2087c98
Remove NOTIFICATION_WEB_CONTENTS_VISIBILITY_CHANGED from download started animations.

BUG=170921
TEST=everything still works

Review URL: https://codereview.chromium.org/26521003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228039 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228039