[Popular Sites] Add Variations parameter to override URL path

components/ntp_tiles/popular_sites_impl_unittest.cc

Index: components/ntp_tiles/popular_sites_impl_unittest.cc
diff --git a/components/ntp_tiles/popular_sites_impl_unittest.cc b/components/ntp_tiles/popular_sites_impl_unittest.cc
index 1deff6bd575927161c6b359c202d504d7595a3c4..044a5d6d3ae72bd3088b71f77e0df6c261a382de 100644
--- a/components/ntp_tiles/popular_sites_impl_unittest.cc
+++ b/components/ntp_tiles/popular_sites_impl_unittest.cc
@@ -458,5 +458,18 @@ TEST_F(PopularSitesTest, RefetchesAfterFallback) {
   EXPECT_THAT(sites[0].url, URLEq("https://www.chromium.org/"));
 }
 
+TEST_F(PopularSitesTest, ShouldOverrideDirectory) {
+  SetCountryAndVersion("ZZ", "9");
+  prefs_->SetString(prefs::kPopularSitesOverrideDirectory, "foo/bar/");
+  RespondWithJSON("https://www.gstatic.com/foo/bar/suggested_sites_ZZ_9.json",
+                  {kWikipedia});
+
+  PopularSites::SitesVector sites;
+  EXPECT_THAT(FetchPopularSites(/*force_download=*/false, &sites),
+              Eq(base::Optional<bool>(true)));
+
+  EXPECT_THAT(sites.size(), Eq(1u));
+}
+
 }  // namespace
 }  // namespace ntp_tiles