GN: app_list_unittests links on Mac.
GN: app_list_unittests links on Mac.

Tested on Mac with the following command lines:
$ gn gen out-gn/Release --args='is_debug=false is_component_build=false symbol_level=1'
$ ninja -C out-gn/Release app_list_unittests

BUG=431177
TEST=see above
R=dpranke@chromium.org

CQ_EXTRA_TRYBOTS=tryserver.chromium.mac:mac_chromium_gn_rel,mac_chromium_gn_dbg

Review URL: https://codereview.chromium.org/1288263002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#343275}

Chilledheart/chromium,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Chilledheart/chromium,axinging/chromium-crosswalk,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,Chilledheart/chromium,axinging/chromium-crosswalk,Chilledheart/chromium,axinging/chromium-crosswalk,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk