Ozone X11 platform

build/config/ui.gni

Index: build/config/ui.gni
diff --git a/build/config/ui.gni b/build/config/ui.gni
index dc7a05905d7f085e525d10754b5b4d3e804b075f..878f465b3b396b4c1f24ae82c06c0f75df974793 100644
--- a/build/config/ui.gni
+++ b/build/config/ui.gni
@@ -20,6 +20,9 @@ declare_args() {
   # that does not require X11.
   use_ozone = false
 
+  # Indicates if Ozone should use X11.
+  use_ozone_x11 = false
+
   # Support ChromeOS touchpad gestures with ozone.
   use_evdev_gestures = false
 
@@ -43,6 +46,10 @@ if (is_linux) {
   use_pango = false
 }
 
+if (use_ozone_x11) {
+  use_ozone = true
+}
+
 # Use GPU accelerated cross process image transport by default on linux builds
 # with the Aura window manager.
 ui_compositor_image_transport = use_aura && is_linux
@@ -50,7 +57,10 @@ ui_compositor_image_transport = use_aura && is_linux
 use_default_render_theme = use_aura || is_linux
 
 # Indicates if the UI toolkit depends on X11.
+# use_x11 specifies if the entire system uses X11-specific code, use_x11_backend
+# specifies if X11 is used as a backend even if use_x11 is off.
 use_x11 = is_linux && !use_ozone
+use_x11_backend = use_x11 || (is_linux && use_ozone && use_ozone_x11)
 
 use_ozone_evdev = use_ozone