Mojo C++ bindings: remove some usage of AssociatedGroup from user code.

services/ui/ws/server_window_delegate.h

Index: services/ui/ws/server_window_delegate.h
diff --git a/services/ui/ws/server_window_delegate.h b/services/ui/ws/server_window_delegate.h
index 71fbdf4858c71c8041448605fda33bb2bbbbdb6d..8caf5bf0b90bd8b2379f31491788a957c681921e 100644
--- a/services/ui/ws/server_window_delegate.h
+++ b/services/ui/ws/server_window_delegate.h
@@ -23,12 +23,6 @@ class ServerWindowDelegate {
   // DisplayCompositor running in the system.
   virtual cc::mojom::DisplayCompositor* GetDisplayCompositor() = 0;
 
-  // Returns the AssociatedGroup of DisplayCompositor which is used for
-  // creating interfaces that share the same MessagePipe with DisplayCompositor.
-  // Messages from interfaces that use the same AssociatedGroup will be
-  // delivered in the same order they were sent.
-  virtual mojo::AssociatedGroup* GetDisplayCompositorAssociatedGroup() = 0;
-
   // Returns the root of the window tree to which this |window| is attached.
   // Returns null if this window is not attached up through to a root window.
   virtual ServerWindow* GetRootWindow(const ServerWindow* window) = 0;