mash: Move directly linked NewWindowDelegate to mojom::NewWindowClient.

ash/common/test/BUILD.gn

Index: ash/common/test/BUILD.gn
diff --git a/ash/common/test/BUILD.gn b/ash/common/test/BUILD.gn
index d47a2a1c2db80cc8be11cfbe48204eeecb0f798b..038998a51d443f9e8cfd2edf644cf0c68c1fdece 100644
--- a/ash/common/test/BUILD.gn
+++ b/ash/common/test/BUILD.gn
@@ -10,6 +10,8 @@ static_library("test_support") {
     "ash_test_impl.h",
     "material_design_controller_test_api.cc",
     "material_design_controller_test_api.h",
+    "test_new_window_client.cc",
+    "test_new_window_client.h",
     "test_palette_delegate.cc",
     "test_palette_delegate.h",
     "test_session_state_delegate.cc",
@@ -33,6 +35,7 @@ static_library("test_support") {
   deps = [
     "//ash",
     "//ash/public/cpp",
+    "//ash/public/interfaces",
     "//base",
     "//components/signin/core/account_id",
     "//components/user_manager",