chromeos: Remove some WmWindow usage from ash/system

ash/system/audio/tray_audio.cc

 // 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.
 
 #include "ash/system/audio/tray_audio.h"
 
 #include "ash/resources/vector_icons/vector_icons.h"
 #include "ash/root_window_controller.h"
+#include "ash/shell.h"
 #include "ash/shell_port.h"
 #include "ash/system/audio/audio_detailed_view.h"
 #include "ash/system/audio/volume_view.h"
 #include "ash/system/tray/system_tray.h"
 #include "ash/system/tray/tray_constants.h"
-#include "ash/wm_window.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "ui/display/display.h"
 #include "ui/display/manager/managed_display_info.h"
 #include "ui/display/screen.h"
 #include "ui/views/view.h"
 
 namespace ash {
 
 using chromeos::CrasAudioHandler;
 using chromeos::DBusThreadManager;
@@ skipping 12 matching lines @@
 TrayAudio::~TrayAudio() {
   DBusThreadManager::Get()->GetPowerManagerClient()->RemoveObserver(this);
   display::Screen::GetScreen()->RemoveObserver(this);
   if (CrasAudioHandler::IsInitialized())
     CrasAudioHandler::Get()->RemoveAudioObserver(this);
 }
 
 // static
 void TrayAudio::ShowPopUpVolumeView() {
   // Show the popup on all monitors with a system tray.
-  for (WmWindow* root : ShellPort::Get()->GetAllRootWindows()) {
-    SystemTray* system_tray = root->GetRootWindowController()->GetSystemTray();
+  for (RootWindowController* root : Shell::GetAllRootWindowControllers()) {

[James Cook, 2017/05/16 22:44:44]

Do we prefer this, RootWindowController::root_window_controllers(), or
ShellPort::Get()->GetAllRootWindows() and lookup each RWC?

[sky, 2017/05/17 16:12:40]

I would like to move to where ShellPort usage is very minimal, and in fact once
I get mash using simplified display management we can get rid of the static
functions that you mention. In other words, what you hae here is great!

+    SystemTray* system_tray = root->GetSystemTray();
     if (!system_tray)
       continue;
     // Show the popup by simulating a volume change. The provided node id and
     // volume value are ignored.
     system_tray->GetTrayAudio()->OnOutputNodeVolumeChanged(0, 0);
   }
 }
 
 bool TrayAudio::GetInitialVisibility() {
   return CrasAudioHandler::Get()->IsOutputMuted();
@@ skipping 135 matching lines @@
     volume_view_->SetVolumeLevel(
         CrasAudioHandler::Get()->GetOutputVolumePercent() / 100.0f);
     volume_view_->Update();
   }
 
   if (audio_detail_view_)
     audio_detail_view_->Update();
 }
 
 }  // namespace ash