Use std::unique_ptr instead of UniquePtr.

Bug: http://b/22403888
Change-Id: I398fa43b8f33c9281d7ff238521d75f1dcb8a5e7
diff --git a/include/utils/LruCache.h b/include/utils/LruCache.h
index 20a379e..1741fb2 100644
--- a/include/utils/LruCache.h
+++ b/include/utils/LruCache.h
@@ -17,10 +17,9 @@
 #ifndef ANDROID_UTILS_LRU_CACHE_H
 #define ANDROID_UTILS_LRU_CACHE_H
 
+#include <memory>
 #include <unordered_set>
 
-#include <UniquePtr.h>
-
 #include "utils/TypeHelpers.h"  // hash_t
 
 namespace android {
@@ -91,7 +90,7 @@
         return result;
     }
 
-    UniquePtr<LruCacheSet> mSet;
+    std::unique_ptr<LruCacheSet> mSet;
     OnEntryRemoved<TKey, TValue>* mListener;
     Entry* mOldest;
     Entry* mYoungest;