Move some File API backend unit tests next to the files that they cover.

storage/browser/BUILD.gn

Index: storage/browser/BUILD.gn
diff --git a/storage/browser/BUILD.gn b/storage/browser/BUILD.gn
index 4fdb007f1debdfe31ef5f825641ae0bf9f97669c..8ab86d85fd7e9e3ef7e2945288741180480d4ecc 100644
--- a/storage/browser/BUILD.gn
+++ b/storage/browser/BUILD.gn
@@ -238,18 +238,29 @@ test("storage_unittests") {
     "database/database_quota_client_unittest.cc",
     "database/database_util_unittest.cc",
     "database/databases_table_unittest.cc",
+    "fileapi/copy_or_move_file_validator_unittest.cc",
     "fileapi/external_mount_points_unittest.cc",
+    "fileapi/file_system_dir_url_request_job_unittest.cc",
+    "fileapi/file_system_file_stream_reader_unittest.cc",
+    "fileapi/file_system_quota_client_unittest.cc",
+    "fileapi/file_system_url_request_job_unittest.cc",
     "fileapi/file_system_url_unittest.cc",
     "fileapi/file_system_usage_cache_unittest.cc",
+    "fileapi/file_writer_delegate_unittest.cc",
     "fileapi/isolated_context_unittest.cc",
     "fileapi/local_file_stream_reader_unittest.cc",
     "fileapi/local_file_stream_writer_unittest.cc",
+    "fileapi/local_file_util_unittest.cc",
     "fileapi/native_file_util_unittest.cc",
+    "fileapi/plugin_private_file_system_backend_unittest.cc",
     "fileapi/quota/quota_backend_impl_unittest.cc",
     "fileapi/quota/quota_reservation_manager_unittest.cc",
+    "fileapi/sandbox_file_system_backend_delegate_unittest.cc",
+    "fileapi/sandbox_file_system_backend_unittest.cc",
     "fileapi/sandbox_isolated_origin_database_unittest.cc",
     "fileapi/sandbox_prioritized_origin_database_unittest.cc",
     "fileapi/timed_task_helper_unittest.cc",
+    "fileapi/transient_file_util_unittest.cc",
   ]
 
   deps = [