Add baked-in favicons for default popular sites on NTP

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 6732e27cc0cca77c40ede17e986c36bc0622432b..32450260d2ea0e3230e1cf345d4f9dc3d8fea8cd 100644
--- a/components/ntp_tiles/popular_sites_impl_unittest.cc
+++ b/components/ntp_tiles/popular_sites_impl_unittest.cc
@@ -6,6 +6,7 @@
 
 #include <map>
 #include <string>
+#include <unordered_set>
 #include <utility>
 #include <vector>
 
@@ -21,6 +22,7 @@
 #include "base/test/sequenced_worker_pool_owner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/values.h"
+#include "components/ntp_tiles/icon_cacher.h"
 #include "components/ntp_tiles/json_unsafe_parser.h"
 #include "components/ntp_tiles/pref_names.h"
 #include "components/ntp_tiles/switches.h"
@@ -63,6 +65,25 @@ size_t GetNumberOfDefaultPopularSitesForPlatform() {
 #endif
 }
 
+class FakeIconCacher : public IconCacher {
+ public:
+  FakeIconCacher() {}
+  ~FakeIconCacher() override {}
+
+  void StartFetch(PopularSites::Site site,
+                  const base::Callback<void(bool)>& done) override {}
+
+  void AddDefaultImage(const PopularSites::Site& site,
+                       int image_resource_id) override {
+    registered_sites_.insert(site.url.spec());
+  }
+
+  size_t GetRegisteredSitesCount() const { return registered_sites_.size(); }
+
+ private:
+  std::unordered_set<std::string> registered_sites_;
+};
+
 class PopularSitesTest : public ::testing::Test {
  protected:
   PopularSitesTest()
@@ -234,6 +255,13 @@ TEST_F(PopularSitesTest, PopulatesWithDefaultResoucesOnFailure) {
   EXPECT_THAT(sites.size(), Eq(GetNumberOfDefaultPopularSitesForPlatform()));
 }
 
+TEST_F(PopularSitesTest, AddsIconUrlsToIconCacher) {
+  auto icon_cacher = base::MakeUnique<FakeIconCacher>();
+  PopularSitesImpl::AddIconsForDefaultPagesToCacher(prefs_, icon_cacher.get());
+  EXPECT_THAT(icon_cacher->GetRegisteredSitesCount(),
+              Eq(GetNumberOfDefaultPopularSitesForPlatform()));
+}
+
 TEST_F(PopularSitesTest, ProvidesDefaultSitesUntilCallbackReturns) {
   SetCountryAndVersion("ZZ", "9");
   RespondWithJSON(