Convert //ash from scoped_ptr to std::unique_ptr

ash/accelerators/magnifier_key_scroller.cc

Index: ash/accelerators/magnifier_key_scroller.cc
diff --git a/ash/accelerators/magnifier_key_scroller.cc b/ash/accelerators/magnifier_key_scroller.cc
index b9cd646d8d454a7eac643005ecf749dd43001991..96a569e1833cd82ef88f44443c8e98499558d0da 100644
--- a/ash/accelerators/magnifier_key_scroller.cc
+++ b/ash/accelerators/magnifier_key_scroller.cc
@@ -36,9 +36,11 @@ void MagnifierKeyScroller::SetEnabled(bool enabled) {
 }
 
 // static
-scoped_ptr<ui::EventHandler> MagnifierKeyScroller::CreateHandler() {
-  scoped_ptr<KeyHoldDetector::Delegate> delegate(new MagnifierKeyScroller());
-  return scoped_ptr<ui::EventHandler>(new KeyHoldDetector(std::move(delegate)));
+std::unique_ptr<ui::EventHandler> MagnifierKeyScroller::CreateHandler() {
+  std::unique_ptr<KeyHoldDetector::Delegate> delegate(
+      new MagnifierKeyScroller());
+  return std::unique_ptr<ui::EventHandler>(
+      new KeyHoldDetector(std::move(delegate)));
 }
 
 bool MagnifierKeyScroller::ShouldProcessEvent(const ui::KeyEvent* event) const {