Ensure PopularSite icon availability in ntp_tiles.

components/ntp_tiles/BUILD.gn

Index: components/ntp_tiles/BUILD.gn
diff --git a/components/ntp_tiles/BUILD.gn b/components/ntp_tiles/BUILD.gn
index e4c919c1a13e6d0edf747bde3e37eb947cdaf210..36e39c06e4c5706fdddf60c6ae15192af2807909 100644
--- a/components/ntp_tiles/BUILD.gn
+++ b/components/ntp_tiles/BUILD.gn
@@ -10,6 +10,8 @@ static_library("ntp_tiles") {
   sources = [
     "constants.cc",
     "constants.h",
+    "icon_cacher.cc",
+    "icon_cacher.h",
     "metrics.cc",
     "metrics.h",
     "most_visited_sites.cc",
@@ -31,7 +33,10 @@ static_library("ntp_tiles") {
   ]
   deps = [
     "//components/data_use_measurement/core",
+    "//components/favicon/core",
+    "//components/favicon_base",
     "//components/google/core/browser",
+    "//components/image_fetcher",
     "//components/pref_registry",
     "//components/prefs",
     "//components/search_engines",
@@ -47,12 +52,18 @@ static_library("ntp_tiles") {
 source_set("unit_tests") {
   testonly = true
   sources = [
+    "icon_cacher_unittest.cc",
     "most_visited_sites_unittest.cc",
   ]
 
   deps = [
     ":ntp_tiles",
+    "//components/favicon/core",
+    "//components/favicon_base",
+    "//components/image_fetcher",
+    "//testing/gmock",
     "//testing/gtest",
+    "//ui/gfx:test_support",
   ]
 }