Sync GN tests with GYP build.

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index ccb580f1dab092a83d7307956864eabd033b4c53..7b7cdb9dbcdf3436d584797beeba35f8f5890af3 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -1251,6 +1251,7 @@ test("base_unittests") {
     "files/file_util_proxy_unittest.cc",
     "files/file_util_unittest.cc",
     "files/important_file_writer_unittest.cc",
+    "files/memory_mapped_file_unittest.cc",
     "files/scoped_temp_dir_unittest.cc",
     "gmock_unittest.cc",
     "guid_unittest.cc",
@@ -1311,6 +1312,7 @@ test("base_unittests") {
     "metrics/field_trial_unittest.cc",
     "metrics/histogram_base_unittest.cc",
     "metrics/histogram_delta_serialization_unittest.cc",
+    "metrics/histogram_macros_unittest.cc",
     "metrics/histogram_snapshot_manager_unittest.cc",
     "metrics/histogram_unittest.cc",
     "metrics/sample_map_unittest.cc",
@@ -1381,6 +1383,7 @@ test("base_unittests") {
     "task_runner_util_unittest.cc",
     "template_util_unittest.cc",
     "test/histogram_tester_unittest.cc",
+    "test/test_pending_task_unittest.cc",
     "test/test_reg_util_win_unittest.cc",
     "test/trace_event_analyzer_unittest.cc",
     "test/user_action_tester_unittest.cc",