In https://chromium-review.googlesource.com/c/chromium/src/+/788394 I tried to remove the default constructed font manager, which we shold remove, as it probably cannot access system fonts in the sandboxed renderer process.

This fact might play into the long standing story we have with missing font handles on Windows.

When trying to remove it in the above CL, a lot of unit tests fail as they rely on this font manager getting constructed with the default constructor.

We need to find a way to have the unit tests have access to fonts, but avoid having the renderer process default construct a SkFontMgr_DWrite.