For =www-client/chromium-44.* widevine support was removed in the Gentoo Ebuild (and was subsequently removed here) because the enabling patch did not work with upstream anymore.
See the related Gentoo bug report, where a patch to re-enable this feature was proposed. I have adapted this patch to the Funtoo Ebuild and tested it. So far it has been working for me without any issues.

Attached you will find

• chromium-44.0.2403.61.ebuild: Patched Ebuild ready to be built (requires chromium-widevine-2403.patch in files/ for building)
• chromium-widevine-ebuild-r11.patch: Patch for chromium-44.* Ebuild
• chromium-widevine-2403.patch: Patch required by the patched chromium Ebuild