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

components/dom_distiller/core/distilled_content_store.cc

Index: components/dom_distiller/core/distilled_content_store.cc
diff --git a/components/dom_distiller/core/distilled_content_store.cc b/components/dom_distiller/core/distilled_content_store.cc
index 11ff967a809905d8a87f9048c8d0c9c344fd5a49..838f9117353041b69717e515c2e3f54e65bb6f00 100644
--- a/components/dom_distiller/core/distilled_content_store.cc
+++ b/components/dom_distiller/core/distilled_content_store.cc
@@ -96,11 +96,11 @@ InMemoryContentStore::CacheDeletor::~CacheDeletor() {
 }
 
 void InMemoryContentStore::CacheDeletor::operator()(
-    const DistilledArticleProto& proto) {
+    DistilledArticleProto* proto) {
   // When InMemoryContentStore is deleted, the |store_| pointer becomes invalid,
   // but since the ContentMap is cleared in the InMemoryContentStore destructor,
   // this should never be called after the destructor.
-  store_->EraseUrlToIdMapping(proto);
+  store_->EraseUrlToIdMapping(*proto);
 }
 
 }  // namespace dom_distiller