Makes Shell::SetDisplayWorkAreaInsets() call to WmShell

ash/aura/wm_shell_aura.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/aura/wm_shell_aura.h"
 
 #include <utility>
 
 #include "ash/aura/key_event_watcher_aura.h"
 #include "ash/aura/pointer_watcher_adapter.h"
@@ skipping 122 matching lines @@
              ->current_default_multi_display_mode() ==
          display::DisplayManager::UNIFIED;
 }
 
 bool WmShellAura::IsForceMaximizeOnFirstRun() {
   return delegate()->IsForceMaximizeOnFirstRun();
 }
 
 void WmShellAura::SetDisplayWorkAreaInsets(WmWindow* window,
                                            const gfx::Insets& insets) {
-  aura::Window* aura_window = WmWindow::GetAuraWindow(window);
-  Shell::GetInstance()->SetDisplayWorkAreaInsets(aura_window, insets);
+  Shell::GetInstance()
+      ->window_tree_host_manager()
+      ->UpdateWorkAreaOfDisplayNearestWindow(window->aura_window(), insets);

[msw, 2017/02/16 18:34:49]

q: what's your advice on using WmWindow::aura_window() vs
WmWindow::GetAuraWindow()? Do you know that this will be non-null, or will we
just handle crashes as they come up? (I'm doing lots of WmWindow<->aura::Window
conversion in my WIP CL to eliminate WmWindowObserver, not sure I'll have a
reasonable CL to eliminate it in one fell swoop)

[sky, 2017/02/16 18:42:20]

Get rid of WmWindow! ;)

Good question. I think it depends upon the code. If the code may pass in null,
then you are right that WmWindow::GetAuraWindow() is safer.
The down stream code
(WindowTreeHostManager::UpdateworkAreaOfDisplayNearestWindow()) crashes on null,
so it seems fair to assume non-null here.

 }
 
 bool WmShellAura::IsPinned() {
   return Shell::GetInstance()->screen_pinning_controller()->IsPinned();
 }
 
 void WmShellAura::SetPinnedWindow(WmWindow* window) {
   return Shell::GetInstance()->screen_pinning_controller()->SetPinnedWindow(
       window);
 }
@@ skipping 154 matching lines @@
   for (auto& observer : display_observers_)
     observer.OnDisplayConfigurationChanging();
 }
 
 void WmShellAura::OnDisplayConfigurationChanged() {
   for (auto& observer : display_observers_)
     observer.OnDisplayConfigurationChanged();
 }
 
 }  // namespace ash