Add unit tests for AddToHomescreenDataFetcher

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index bee53fb1c0c4cb0e4e360d5393358f0ec63d4613..956efd18fdea231efd7a25ef5f155af26477d5da 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -25,6 +25,8 @@ static_library("test_support") {
   sources = [
     "../browser/download/mock_download_file.cc",
     "../browser/download/mock_download_file.h",
+    "../browser/service_worker/embedded_worker_test_helper.cc",
+    "../browser/service_worker/embedded_worker_test_helper.h",
     "../public/test/async_file_test_helper.cc",
     "../public/test/async_file_test_helper.h",
     "../public/test/background_sync_test_util.cc",
@@ -1183,8 +1185,6 @@ test("content_unittests") {
     "../browser/renderer_host/text_input_client_mac_unittest.mm",
     "../browser/resolve_proxy_msg_helper_unittest.cc",
     "../browser/service_worker/embedded_worker_instance_unittest.cc",
-    "../browser/service_worker/embedded_worker_test_helper.cc",
-    "../browser/service_worker/embedded_worker_test_helper.h",
     "../browser/service_worker/link_header_support_unittest.cc",
     "../browser/service_worker/service_worker_cache_writer_unittest.cc",
     "../browser/service_worker/service_worker_context_core_unittest.cc",