Linux Add liberation-fonts as a RPM dependency.

Previously, all supported distros had it except for RHEL 7. Now RHEL 7
has it too. https://access.redhat.com/errata/RHEA-2018:0817

Change-Id: I667ac877c76efd3369ce634da5be5e2d6c86ee9e
Reviewed-on: https://chromium-review.googlesource.com/1159995Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#580919}

chrome/installer/linux/rpm/additional_deps

@@ -3,9 +3,6 @@
 # found in the LICENSE file.
 #
 # Additional dependencies not in the rpm find-requires output.
-#
-# TODO(thestig,bugzilla.redhat.com/show_bug.cgi?id=1482760): Use the
-# liberation-fonts package once it's available on all distros.
 
 # For lsb_release.
 /usr/bin/lsb_release
@@ -16,6 +13,9 @@ ca-certificates
 # Temporary entry for tray icons
 libappindicator3.so.1()(64bit)
 
+# Make sure users have compatible fonts for viewing PDFs.
+liberation-fonts
+
 # Specify a more recent version for security and stability updates. While we
 # depend on libnss3.so and not libssl3.so, force the dependency on libssl3 to
 # ensure the NSS version is 3.28 or later, since libssl3 should always be