Remove some linked_ptr c/b/extension

chrome/browser/extensions/api/mdns/dns_sd_registry.h

Index: chrome/browser/extensions/api/mdns/dns_sd_registry.h
diff --git a/chrome/browser/extensions/api/mdns/dns_sd_registry.h b/chrome/browser/extensions/api/mdns/dns_sd_registry.h
index d85f297fdc57b70871dbec31fda5b8d52e9d9dde..4f342684288dcf6015ecb1519cdf135d6e816659 100644
--- a/chrome/browser/extensions/api/mdns/dns_sd_registry.h
+++ b/chrome/browser/extensions/api/mdns/dns_sd_registry.h
@@ -12,7 +12,6 @@
 #include <vector>
 
 #include "base/macros.h"
-#include "base/memory/linked_ptr.h"
 #include "base/observer_list.h"
 #include "chrome/browser/extensions/api/mdns/dns_sd_delegate.h"
 
@@ -94,10 +93,6 @@ class DnsSdRegistry : public DnsSdDelegate {
     DISALLOW_COPY_AND_ASSIGN(ServiceTypeData);
   };
 
-  // Maps service types to associated data such as listers and service lists.
-  typedef std::map<std::string, linked_ptr<ServiceTypeData> >
-      DnsSdServiceTypeDataMap;
-
   virtual DnsSdDeviceLister* CreateDnsSdDeviceLister(
       DnsSdDelegate* delegate,
       const std::string& service_type,
@@ -111,7 +106,7 @@ class DnsSdRegistry : public DnsSdDelegate {
                       const std::string& service_name) override;
   void ServicesFlushed(const std::string& service_type) override;
 
-  DnsSdServiceTypeDataMap service_data_map_;
+  std::map<std::string, std::unique_ptr<ServiceTypeData>> service_data_map_;
 
  private:
   void DispatchApiEvent(const std::string& service_type);