Removes some dead code

ash/mus/bridge/wm_root_window_controller_mus.cc

 // Copyright 2016 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.
 
 #include "ash/mus/bridge/wm_root_window_controller_mus.h"
 
 #include "ash/mus/bridge/wm_shelf_mus.h"
 #include "ash/mus/bridge/wm_shell_mus.h"
 #include "ash/mus/bridge/wm_window_mus.h"
 #include "ash/mus/root_window_controller.h"
@@ skipping 44 matching lines @@
 
 gfx::Point WmRootWindowControllerMus::ConvertPointToScreen(
     const WmWindowMus* source,
     const gfx::Point& point) const {
   gfx::Point point_in_root =
       source->ConvertPointToTarget(source->GetRootWindow(), point);
   point_in_root += GetDisplay().bounds().OffsetFromOrigin();
   return point_in_root;
 }
 
-gfx::Point WmRootWindowControllerMus::ConvertPointFromScreen(
-    const WmWindowMus* target,
-    const gfx::Point& point) const {
-  gfx::Point result = point;
-  result -= GetDisplay().bounds().OffsetFromOrigin();
-  return target->GetRootWindow()->ConvertPointToTarget(target, result);
-}
-
 const display::Display& WmRootWindowControllerMus::GetDisplay() const {
   return root_window_controller_->display();
 }
 
 void WmRootWindowControllerMus::MoveWindowsTo(WmWindow* dest) {
   WmRootWindowController::MoveWindowsTo(dest);
 }
 
 bool WmRootWindowControllerMus::HasShelf() {
   return GetShelf() != nullptr;
@@ skipping 41 matching lines @@
   aura::WindowTreeClient* window_tree_client =
       root_window_controller_->window_manager()->window_tree_client();
   aura::Window* aura_window = WmWindowMus::GetAuraWindow(window);
   aura::WindowMus* window_mus = aura::WindowMus::Get(aura_window);
   return window_tree_client->WasCreatedByThisClient(window_mus) ||
          window_tree_client->IsRoot(window_mus);
 }
 
 }  // namespace mus
 }  // namespace ash