Mus-WS / Aura-Mus: Propagate LocalSurfaceId on WindowTreeHost creation

services/ui/public/interfaces/window_tree.mojom

Index: services/ui/public/interfaces/window_tree.mojom
diff --git a/services/ui/public/interfaces/window_tree.mojom b/services/ui/public/interfaces/window_tree.mojom
index 3d9a6db1bf74d5bbf2fac057750d8ec4a26c85a3..84d5ab7ca36d1bfef79c9585a0404566275e79f4 100644
--- a/services/ui/public/interfaces/window_tree.mojom
+++ b/services/ui/public/interfaces/window_tree.mojom
@@ -6,6 +6,7 @@ module ui.mojom;
 
 import "cc/ipc/frame_sink_id.mojom";
 import "cc/ipc/local_surface_id.mojom";
+import "cc/ipc/surface_id.mojom";
 import "cc/ipc/surface_info.mojom";
 import "cc/ipc/mojo_compositor_frame_sink.mojom";
 import "services/ui/public/interfaces/cursor.mojom";
@@ -328,14 +329,17 @@ interface WindowTreeClient {
   // the window manager service, unless the connection is to the root connection
   // in which case it will be null. |parent_drawn| is true if roots parent is
   // drawn, see OnParentDrawnStateChanged() for details. |display_id| identifies
-  // the display this root window is on.
+  // the display this root window is on. |frame_sink_id| uniquely identifies the
+  // client in the display compositor. If the embedded window has a size,
+  // |local_surface_id| identifies the ID to use to submit CompositorFrames.
   OnEmbed(uint16 connection_id,
           WindowData root,
           WindowTree? tree,
           int64 display_id,
           uint32 focused_window,
           bool parent_drawn,
-          cc.mojom.FrameSinkId frame_sink_id);
+          cc.mojom.FrameSinkId frame_sink_id,
+          cc.mojom.LocalSurfaceId? local_surface_id);
 
   // Invoked when the application embedded at |window| is disconnected. In other
   // words the embedded app closes the connection to the server. This is called
@@ -359,12 +363,15 @@ interface WindowTreeClient {
   // Called in response to NewTopLevelWindow() successfully completing.
   // |parent_drawn| is true if the parent of the window is drawn, see
   // OnDrawnStateChanged() for details. |display_id| identifies the display this
-  // window is on.
+  // window is on. |frame_sink_id| uniquely identifies the client in the display
+  // compositor. If the top level window has a size, |local_surface_id|
+  // identifies the ID to use to submit CompositorFrames.
   OnTopLevelCreated(uint32 change_id,
                     WindowData data,
                     int64 display_id,
                     bool parent_drawn,
-                    cc.mojom.FrameSinkId frame_sink_id);
+                    cc.mojom.FrameSinkId frame_sink_id,
+                    cc.mojom.LocalSurfaceId? local_surface_id);
 
   // Invoked when a window's bounds have changed. Only the client embedded in
   // |window| gets a non_empty |local_surface_id|.