Only send the FrameSinkId to client when it is necessary

services/ui/public/interfaces/window_tree.mojom

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 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";
@@ skipping 309 matching lines @@
 // Changes to windows are not sent to the connection that originated the
 // change. For example, if connection 1 changes the bounds of a window by
 // calling SetWindowBounds(), connection 1 does not receive
 // OnWindowBoundsChanged().
 interface WindowTreeClient {
   // Invoked when the client application has been embedded at |root|.
   // See Embed() on WindowTree for more details. |tree| will be a handle back to
   // 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. |frame_sink_id| uniquely identifies the
-  // client in the frame sink manager. If the embedded window has a size,
+  // the display this root window is on. 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.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
   // on the connection that created |window| as well as any ancestors that have
   // the embed root policy.
   OnEmbeddedAppDisconnected(uint32 window);
 
   // Sent when another connection is embedded in the Window this connection was
   // previously embedded in. See Embed() for more information.
   OnUnembed(uint32 window);
 
   // Sent when capture changes. This is not sent if the client initiated the
   // change.
   OnCaptureChanged(uint32 new_capture, uint32 old_capture);
 
   // This is called on the owner of a window when it embeds a client in it,
   // which includes the window manager creating a new window at the request of
   // another client.
   OnFrameSinkIdAllocated(uint32 window, cc.mojom.FrameSinkId frame_sink_id);
 
   // 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. |frame_sink_id| uniquely identifies the client in the display
-  // compositor. If the top level window has a size, |local_surface_id|
+  // window is on. 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.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|.
   OnWindowBoundsChanged(uint32 window,
                         gfx.mojom.Rect old_bounds,
                         gfx.mojom.Rect new_bounds,
                         cc.mojom.LocalSurfaceId? local_surface_id);
 
   OnClientAreaChanged(uint32 window_id,
@@ skipping 148 matching lines @@
   // See description of WindowManager for details.
   GetWindowManager(associated WindowManager& internal);
 };
 
 // Mus provides this interface as a way for clients to connect and obtain a
 // WindowTree handle with a supplied WindowTreeClient handle. The
 // WindowTreeClient has no roots, use NewTopLevelWindow() to create one.
 interface WindowTreeFactory {
   CreateWindowTree(WindowTree& tree_request, WindowTreeClient client);
 };