Fix GN visibility for a few targets that are compiled by default in a GN build.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 2ba8e1faee9504de493968f51d0c98416176db1e..7f497fa984a3f977d502f857473a953adc45e8da 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -24,7 +24,7 @@ declare_args() {
   root_extra_deps = []
 }
 
-# This file defines the following three main targets:
+# This file defines the following four main targets:
 #
 # "both_gn_and_gyp" should list every root target (target that nothing else
 # depends on) built by GN that is also built in the GYP build.
@@ -37,6 +37,11 @@ declare_args() {
 # build is, this may end up including targets that are actually defined in a
 # GYP build but not dependencies of GYP's "all" (and so not actually built).
 #
+# "gn_visibility": targets that are normally not visible to top-level targets,
+# but are built anyway by "all". Since we don't want any such targets, we
+# have this placeholder to make sure hidden targets that aren't otherwise
+# depended on yet are accounted for.
+#
 # TODO(GYP): crbug.com/481694. Make sure that the above is true and there are
 # scripts run on the bots that enforce this. Once the GYP migration is over,
 # we can collapse all of these targets as desired.
@@ -47,6 +52,7 @@ group("gn_all") {
   deps = [
     ":both_gn_and_gyp",
     ":gn_only",
+    ":gn_visibility",
   ]
 }
 
@@ -701,10 +707,13 @@ group("gn_mojo_targets") {
 
 group("gn_visibility") {
   deps = [
-    # "//build/config/sanitizers:options_sources",
+    "//build/config/sanitizers:options_sources",
+
     # "//third_party/pdfium:pdfium_embeddertests",  # TODO(GYP): visibility?
     # "//third_party/pdfium:pdfium_unittests",  # TODO(GYP): visibility?
-    # "//ui/resources:repack_ui_test_mac_locale_pack",
+
+    "//ui/resources:repack_ui_test_mac_locale_pack",
+
     # "//v8:v8_snapshot",  # TODO(GYP): visibility?
     # "//v8:postmortem-metadata",  # TODO(GYP): visibility?
   ]