farout ~ # emerge -pv chromium

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild     U *] media-video/ffmpeg-9999:0/56.58.58::media-kit [3.4.1:0/55.57.57::media-kit] USE="X alsa amr bs2b bzip2 cdio encode gmp gpl hardcoded-tables iconv ieee1394 jpeg2k libass libv4l mp3 network openal opengl openh264 openssl oss pic postproc sdl speex svg theora threads truetype twolame v4l vaapi vorbis vpx wavpack webp x264 x265 xvid zlib (-altivec) -amrenc -appkit -bluray -celt -chromaprint -chromium -cpudetection -debug -doc -fdk -flite -fontconfig -frei0r -fribidi -gcrypt -gme -gnutls -gsm -iec61883 -jack -kvazaar -ladspa -libcaca -libilbc -librtmp -libsoxr -lzma (-mipsdspr1) (-mipsdspr2) (-mipsfpu) (-mmal) -modplug -nvenc -opus -pulseaudio -rubberband -samba -snappy -ssh -static-libs {-test} -vdpau -xcb -zeromq -zimg -zvbi" CPU_FLAGS_X86="aes avx avx2 fma3 mmx mmxext sse sse2 sse3 sse4_1 sse4_2 ssse3 -3dnow -3dnowext -fma4 -xop" FFTOOLS="aviocat cws2fws ffescape ffeval ffhash fourcc2pixfmt graph2dot ismindex pktdumper qt-faststart sidxindex trasher" 0 KiB
[ebuild     U #] www-client/chromium-68.0.3438.3::net-kit [66.0.3359.181::net-kit] USE="jumbo-build (pic) proprietary-codecs suid system-ffmpeg -component-build -cups -custom-cflags -gnome-keyring -hangouts -kerberos (-neon) -pulseaudio (-selinux) (-system-icu) (-system-libvpx) (-tcmalloc) -widevine" L10N="de en-GB es es-419 -am -ar -bg -bn -ca -cs -da -el -et -fa -fi -fil -fr -gu -he -hi -hr -hu -id -it -ja -kn -ko -lt -lv -ml -mr -ms -nb -nl -pl -pt-BR -pt-PT -ro -ru -sk -sl -sr -sv -sw -ta -te -th -tr -uk -vi -zh-CN -zh-TW" 609'814 KiB

Total: 2 packages (2 upgrades), Size of downloads: 609'814 KiB

The following keyword changes are necessary to proceed:
 (see "package.accept_keywords" in the portage(5) man page for more details)
# required by media-plugins/alsa-plugins-1.1.5::media-kit[ffmpeg]
# required by @selected
# required by @world (argument)
=media-video/ffmpeg-9999 **

The following mask changes are necessary to proceed:
 (see "package.unmask" in the portage(5) man page for more details)
# required by chromium (argument)
# /var/git/meta-repo/kits/core-kit/profiles/package.mask/00-gentoo:
# Mike Gilbert <floppym@gentoo.org> (24 Mar 2018)
# # Dev channel releases are only for people who are developers or want more
# # experimental features and accept a more unstable release.
=www-client/chromium-68.0.3438.3

NOTE: The --autounmask-keep-masks option will prevent emerge
      from creating package.unmask or ** keyword changes.

 * In order to avoid wasting time, backtracking has terminated early
 * due to the above autounmask change(s). The --autounmask-backtrack=y
 * option can be used to force further backtracking, but there is no
 * guarantee that it will produce a solution.

farout ~ # ls -l /var/git/meta-repo/kits/net-kit/www-client/chromium/
total 108
-rw-r--r-- 1 portage portage  1266 Jun 10 07:11 Manifest
-rw-r--r-- 1 portage portage 20544 Jun 10 07:11 chromium-67.0.3396.62.ebuild
-rw-r--r-- 1 portage portage 20545 Jun 10 07:11 chromium-67.0.3396.79.ebuild
-rw-r--r-- 1 portage portage 21136 Jun 10 07:11 chromium-68.0.3409.2.ebuild
-rw-r--r-- 1 portage portage 20529 Jun 10 07:11 chromium-68.0.3438.3.ebuild
drwxr-xr-x 2 portage portage  4096 Jun 10 07:11 files
-rw-r--r-- 1 portage portage  1418 Jan  7 08:20 metadata.xml
farout ~ #