Make chrome --mus run the UI Service inside the browser process.

chrome/browser/browser_process_platform_part_chromeos.h

Index: chrome/browser/browser_process_platform_part_chromeos.h
diff --git a/chrome/browser/browser_process_platform_part_chromeos.h b/chrome/browser/browser_process_platform_part_chromeos.h
index 657c817a4ae11c84bf265ce01eea73d6a3a341e1..6aaaed868e2bef9776b6b9060581ee94cf59922f 100644
--- a/chrome/browser/browser_process_platform_part_chromeos.h
+++ b/chrome/browser/browser_process_platform_part_chromeos.h
@@ -13,6 +13,7 @@
 #include "base/macros.h"
 #include "base/sequence_checker.h"
 #include "chrome/browser/browser_process_platform_part_base.h"
+#include "services/ui/common/image_cursors_set.h"
 
 namespace chromeos {
 class ChromeSessionManager;
@@ -140,6 +141,9 @@ class BrowserProcessPlatformPart : public BrowserProcessPlatformPartBase {
 
   base::flat_set<std::string> compatible_cros_components_;
 
+  // Used by the UI Service.
+  ui::ImageCursorsSet image_cursors_set_;
+
 #if defined(USE_OZONE)
   std::unique_ptr<ui::InputDeviceControllerClient>
       input_device_controller_client_;