Convert //ash from scoped_ptr to std::unique_ptr

ash/shelf/shelf_navigator_unittest.cc

Index: ash/shelf/shelf_navigator_unittest.cc
diff --git a/ash/shelf/shelf_navigator_unittest.cc b/ash/shelf/shelf_navigator_unittest.cc
index bb3d5043c9677f150bd8a509f48456179a8c2381..5464a7d2bd35cc38f9e240d2e99aed217f2a64b3 100644
--- a/ash/shelf/shelf_navigator_unittest.cc
+++ b/ash/shelf/shelf_navigator_unittest.cc
@@ -64,7 +64,7 @@ class ShelfNavigatorTest : public testing::Test {
   const ShelfModel& model() { return *model_.get(); }
 
  private:
-  scoped_ptr<ShelfModel> model_;
+  std::unique_ptr<ShelfModel> model_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfNavigatorTest);
 };