base: Remove non-const refs from the MRUCache implementation.

base/containers/mru_cache.h

Index: base/containers/mru_cache.h
diff --git a/base/containers/mru_cache.h b/base/containers/mru_cache.h
index 15ea2fccdc4104dfbae4961cc24674c475230771..30974514244d2ed29bbfa47e9f398107d1b7dfb4 100644
--- a/base/containers/mru_cache.h
+++ b/base/containers/mru_cache.h
@@ -140,7 +140,7 @@ class MRUCacheBase {
   // Erases the item referenced by the given iterator. An iterator to the item
   // following it will be returned. The iterator must be valid.
   iterator Erase(iterator pos) {
-    deletor_(pos->second);
+    deletor_(&pos->second);
     index_.erase(pos->first);
     return ordering_.erase(pos);
   }
@@ -165,7 +165,7 @@ class MRUCacheBase {
   void Clear() {
     for (typename PayloadList::iterator i(ordering_.begin());
          i != ordering_.end(); ++i)
-      deletor_(i->second);
+      deletor_(&i->second);
     index_.clear();
     ordering_.clear();
   }
@@ -213,8 +213,7 @@ class MRUCacheBase {
 template<class PayloadType>
 class MRUCacheNullDeletor {
  public:
-  void operator()(PayloadType& payload) {
-  }
+  void operator()(PayloadType* payload) {}
 };
 
 // A container that does not do anything to free its data. Use this when storing
@@ -244,9 +243,7 @@ class MRUCache : public MRUCacheBase<KeyType,
 template<class PayloadType>
 class MRUCachePointerDeletor {
  public:
-  void operator()(PayloadType& payload) {
-    delete payload;
-  }
+  void operator()(PayloadType* payload) { delete *payload; }

[Nico, 2015/03/07 01:06:14]

can't you just make this const PalyloadType& ? I think deleting const refs
should be ok?

 };
 
 // A cache that owns the payload type, which must be a non-const pointer type.