Makes WindowTree::DeleteWindow() unembed for roots

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/surface_id.mojom";
 import "services/ui/public/interfaces/cursor.mojom";
 import "services/ui/public/interfaces/event_matcher.mojom";
 import "services/ui/public/interfaces/mus_constants.mojom";
@@ skipping 47 matching lines @@
   // Requests the WindowManager to create a new top level window. On success
   // OnTopLevelCreated() is called with the WindowData for the new window. On
   // failure OnChangeCompleted() is called.
   // TODO(sky): this likely needs context, maybe in |properties|.
   NewTopLevelWindow(uint32 change_id,
                     uint32 window_id,
                     map<string, array<uint8>> properties);
 
   // Deletes a window. This does not recurse. No hierarchy change notifications
   // are sent as a result of this. Only the connection that created the window
-  // can delete it.
+  // can delete it. DeleteWindow() may also be used to remove a window as an
+  // embed root from the client. When DeleteWindow() is used to remove an embed
+  // root, the client no longer has access to the embed root. The embedder of
+  // the root is notified of the change via OnEmbeddedAppDisconnected().
   DeleteWindow(uint32 change_id, uint32 window_id);
 
   // Requests input event capture for the given |window_id|. Capture is only
   // allowed if the window is processing an event. When a window gains capture,
   // current input events are canceled. The given window will receive all
   // subsequent input until an alternate window is set via SetCapture, or
   // ReleaseCapture is called for |window_id|. OnCaptureChanged() is called to
   // notify of capture changing (as long as the client did not initiate the
   // change).
   SetCapture(uint32 change_id, uint32 window_id);
@@ skipping 386 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);
 };