Moves maintaining ShellObservers back to Shell

chrome/browser/chromeos/policy/display_rotation_default_handler.cc

Index: chrome/browser/chromeos/policy/display_rotation_default_handler.cc
diff --git a/chrome/browser/chromeos/policy/display_rotation_default_handler.cc b/chrome/browser/chromeos/policy/display_rotation_default_handler.cc
index 0e083584c6f975a81955a8f1a0ac0a4da523317c..1fd8ae5810a95dc65d24cf2d0662caa92c1b2dfe 100644
--- a/chrome/browser/chromeos/policy/display_rotation_default_handler.cc
+++ b/chrome/browser/chromeos/policy/display_rotation_default_handler.cc
@@ -22,7 +22,7 @@ namespace policy {
 
 DisplayRotationDefaultHandler::DisplayRotationDefaultHandler() {
   ash::Shell::GetInstance()->window_tree_host_manager()->AddObserver(this);
-  ash::WmShell::Get()->AddShellObserver(this);
+  ash::Shell::GetInstance()->AddShellObserver(this);
   settings_observer_ = chromeos::CrosSettings::Get()->AddSettingsObserver(
       chromeos::kDisplayRotationDefault,
       base::Bind(&DisplayRotationDefaultHandler::OnCrosSettingsChanged,
@@ -43,7 +43,7 @@ void DisplayRotationDefaultHandler::OnDisplayConfigurationChanged() {
 
 void DisplayRotationDefaultHandler::OnWindowTreeHostManagerShutdown() {
   ash::Shell::GetInstance()->window_tree_host_manager()->RemoveObserver(this);
-  ash::WmShell::Get()->RemoveShellObserver(this);
+  ash::Shell::GetInstance()->RemoveShellObserver(this);
   settings_observer_.reset();
   base::ThreadTaskRunnerHandle::Get()->DeleteSoon(FROM_HERE, this);
 }