Broke out layout metric information from ViewsDelegate to LayoutProvider

ash/mus/app_launch_unittest.cc

Index: ash/mus/app_launch_unittest.cc
diff --git a/ash/mus/app_launch_unittest.cc b/ash/mus/app_launch_unittest.cc
index e9a3e6074cf77eec2d17384f73a4e8f413c626b5..157e492d5a82107708121bdc47a515b73d57cca3 100644
--- a/ash/mus/app_launch_unittest.cc
+++ b/ash/mus/app_launch_unittest.cc
@@ -10,6 +10,7 @@
 #include "services/service_manager/public/cpp/service_test.h"
 #include "services/ui/public/interfaces/constants.mojom.h"
 #include "services/ui/public/interfaces/window_server_test.mojom.h"
+#include "ui/views/layout/layout_provider.h"
 
 namespace ash {
 namespace mus {
@@ -30,6 +31,8 @@ class AppLaunchTest : public service_manager::test::ServiceTest {
     ServiceTest::SetUp();
   }
 
+  views::LayoutProvider layout_provider_;
+
   DISALLOW_COPY_AND_ASSIGN(AppLaunchTest);
 };