mash: Migrate ScopedTargetRootWindow to //ash/common

ash/common/wm/window_positioner.cc

 // Copyright 2013 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/common/wm/window_positioner.h"
 
 #include "ash/common/wm/mru_window_tracker.h"
 #include "ash/common/wm/window_positioning_utils.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm/wm_screen_util.h"
@@ skipping 199 matching lines @@
 }
 
 // static
 void WindowPositioner::GetBoundsAndShowStateForNewWindow(
     const WmWindow* new_window,
     bool is_saved_bounds,
     ui::WindowShowState show_state_in,
     gfx::Rect* bounds_in_out,
     ui::WindowShowState* show_state_out) {
   // Always open new window in the target display.
-  WmWindow* target = WmShell::Get()->GetRootWindowForNewWindows();
+  WmWindow* target = WmShell::Get()->root_window_for_new_windows();
 
   WmWindow* top_window = GetReferenceWindow(target, nullptr, nullptr);
   // Our window should not have any impact if we are already on top.
   if (top_window == new_window)
     top_window = nullptr;
 
   // If there is no valid other window we take and adjust the passed coordinates
   // and show state.
   if (!top_window) {
     gfx::Rect work_area = target->GetDisplayNearestWindow().work_area();
@@ skipping 324 matching lines @@
   // If the alignment was pushing the window out of the screen, we ignore the
   // alignment for that call.
   if (abs(pos.right() - work_area.right()) < grid)
     x = work_area.right() - w;
   if (abs(pos.bottom() - work_area.bottom()) < grid)
     y = work_area.bottom() - h;
   return gfx::Rect(x, y, w, h);
 }
 
 }  // namespace ash