Some easy linked_ptr removal from extensions/common/

extensions/common/event_filter.cc

Index: extensions/common/event_filter.cc
diff --git a/extensions/common/event_filter.cc b/extensions/common/event_filter.cc
index 2a16678cbdf2026aa6e327bd73861f27fb8f7490..fa587016ba3480f1a7f9c9c24b54b08d4c898422 100644
--- a/extensions/common/event_filter.cc
+++ b/extensions/common/event_filter.cc
@@ -7,6 +7,7 @@
 #include <string>
 #include <utility>
 
+#include "base/memory/ptr_util.h"
 #include "components/url_matcher/url_matcher_factory.h"
 #include "ipc/ipc_message.h"
 
@@ -67,8 +68,8 @@ EventFilter::MatcherID EventFilter::AddEventMatcher(
         std::make_pair((*it)->id(), id));
   }
   id_to_event_name_[id] = event_name;
-  event_matchers_[event_name][id] = linked_ptr<EventMatcherEntry>(
-      new EventMatcherEntry(std::move(matcher), &url_matcher_, condition_sets));
+  event_matchers_[event_name][id] = base::MakeUnique<EventMatcherEntry>(
+      std::move(matcher), &url_matcher_, condition_sets);
   return id;
 }