Extend LargeIconService to fetch missing favicons from a Google server

ios/chrome/app/spotlight/spotlight_manager_unittest.mm

Index: ios/chrome/app/spotlight/spotlight_manager_unittest.mm
diff --git a/ios/chrome/app/spotlight/spotlight_manager_unittest.mm b/ios/chrome/app/spotlight/spotlight_manager_unittest.mm
index 7051af7132508ca2c856d735fd9ac4e43d74fe0e..3bc30c0df0c944c1bc28b39ec9c6f3ac0eae0418 100644
--- a/ios/chrome/app/spotlight/spotlight_manager_unittest.mm
+++ b/ios/chrome/app/spotlight/spotlight_manager_unittest.mm
@@ -67,7 +67,8 @@ class SpotlightManagerTest : public testing::Test {
   SpotlightManagerTest() {
     model_ = bookmarks::TestBookmarkClient::CreateModel();
     large_icon_service_.reset(new favicon::LargeIconService(
-        &mock_favicon_service_, base::ThreadTaskRunnerHandle::Get()));
+        &mock_favicon_service_, base::ThreadTaskRunnerHandle::Get(),
+        /*image_fetcher=*/nullptr));
     bookmarksSpotlightManager_ = [[BookmarksSpotlightManager alloc]
         initWithLargeIconService:large_icon_service_.get()
                    bookmarkModel:model_.get()];