Reduce the use of ui::ScaleFactor in webui/favicon

First step for renaming ui::ScaleFactor to ui::ResourceScaleFactor

BUG=372212
[email protected], [email protected]

Review URL: https://codereview.chromium.org/291733004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271909 0039d316-1c4b-4281-b951-d872f2087c98
13 files changed