ozone: Introduce ClientPixmap and ClientPixmapFactory for non-GPU processes.

ui/ozone/platform/drm/ozone_platform_drm.h

Index: ui/ozone/platform/drm/ozone_platform_drm.h
diff --git a/ui/ozone/platform/drm/ozone_platform_drm.h b/ui/ozone/platform/drm/ozone_platform_drm.h
index 5837870d15bc6d88842d051faa6de9d58b9460f1..33ee5e0fa877f1ecc4100d40bd84ef951373f803 100644
--- a/ui/ozone/platform/drm/ozone_platform_drm.h
+++ b/ui/ozone/platform/drm/ozone_platform_drm.h
@@ -7,6 +7,7 @@
 
 namespace ui {
 
+class OzoneClient;
 class OzonePlatform;
 
 // Constructor hook for use in ozone_platform_list.cc
@@ -14,6 +15,11 @@ OzonePlatform* CreateOzonePlatformDri();
 
 OzonePlatform* CreateOzonePlatformDrm();
 
+// Constructor hook for use in constructor_client_list.cc
+OzoneClient* CreateOzoneClientDri();
+
+OzoneClient* CreateOzoneClientDrm();
+
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRM_OZONE_PLATFORM_DRM_H_