Remove linked_ptr from ash

ash/wm/resize_shadow_controller.cc

Index: ash/wm/resize_shadow_controller.cc
diff --git a/ash/wm/resize_shadow_controller.cc b/ash/wm/resize_shadow_controller.cc
index c0d29ce136caf6f47027772d33183853d56a1fc7..8950d2baee43ae24fd7ae54d95338cc2774da1f0 100644
--- a/ash/wm/resize_shadow_controller.cc
+++ b/ash/wm/resize_shadow_controller.cc
@@ -14,10 +14,8 @@ namespace ash {
 ResizeShadowController::ResizeShadowController() {}
 
 ResizeShadowController::~ResizeShadowController() {
-  for (WindowShadowMap::const_iterator it = window_shadows_.begin();
-       it != window_shadows_.end(); ++it) {
-    it->first->RemoveObserver(this);
-  }
+  for (const auto& shadow : window_shadows_)
+    shadow.first->RemoveObserver(this);
 }
 
 void ResizeShadowController::ShowShadow(aura::Window* window, int hit_test) {
@@ -52,20 +50,22 @@ void ResizeShadowController::OnWindowDestroyed(aura::Window* window) {
 }
 
 ResizeShadow* ResizeShadowController::CreateShadow(aura::Window* window) {
-  linked_ptr<ResizeShadow> shadow(new ResizeShadow());
-  window_shadows_.insert(std::make_pair(window, shadow));
+  auto shadow = base::MakeUnique<ResizeShadow>();
   // Attach the layers to this window.
   shadow->Init(window);
   // Ensure initial bounds are correct.
   shadow->Layout(window->bounds());
   // Watch for bounds changes.
   window->AddObserver(this);
-  return shadow.get();
+
+  ResizeShadow* raw_shadow = shadow.get();
+  window_shadows_.insert(std::make_pair(window, std::move(shadow)));
+  return raw_shadow;
 }
 
 ResizeShadow* ResizeShadowController::GetShadowForWindow(aura::Window* window) {
-  WindowShadowMap::const_iterator it = window_shadows_.find(window);
-  return it != window_shadows_.end() ? it->second.get() : NULL;
+  auto it = window_shadows_.find(window);
+  return it != window_shadows_.end() ? it->second.get() : nullptr;
 }
 
 }  // namespace ash