--- a/netwerk/dns/nsDNSService2.cpp
+++ b/netwerk/dns/nsDNSService2.cpp
@@ -152,17 +152,17 @@ nsDNSRecord::GetNextAddr(uint16_t port, 
         mHostRecord->addr_info_lock.Unlock();
 
         if (!mHostRecord->addr) {
             // Both mHostRecord->addr_info and mHostRecord->addr are null.
             // This can happen if mHostRecord->addr_info expired and the
             // attempt to reresolve it failed.
             return NS_ERROR_NOT_AVAILABLE;
         }
-        memcpy(addr, mHostRecord->addr, sizeof(NetAddr));
+        memcpy(addr, mHostRecord->addr.get(), sizeof(NetAddr));
         mDone = true;
     }
 
     // set given port
     port = htons(port);
     if (addr->raw.family == AF_INET) {
         addr->inet.port = port;
     } else if (addr->raw.family == AF_INET6) {
@@ -197,17 +197,17 @@ nsDNSRecord::GetAddresses(nsTArray<NetAd
         mHostRecord->addr_info_lock.Unlock();
     } else {
         mHostRecord->addr_info_lock.Unlock();
 
         if (!mHostRecord->addr) {
             return NS_ERROR_NOT_AVAILABLE;
         }
         NetAddr *addr = aAddressArray.AppendElement(NetAddr());
-        memcpy(addr, mHostRecord->addr, sizeof(NetAddr));
+        memcpy(addr, mHostRecord->addr.get(), sizeof(NetAddr));
         if (addr->raw.family == AF_INET) {
             addr->inet.port = 0;
         } else if (addr->raw.family == AF_INET6) {
             addr->inet6.port = 0;
         }
     }
     return NS_OK;
 }

--- a/netwerk/dns/nsHostResolver.cpp
+++ b/netwerk/dns/nsHostResolver.cpp
@@ -227,17 +227,16 @@ nsHostRecord::CopyExpirationTimesAndFlag
     mGraceStart = aFromHostRecord->mGraceStart;
     mDoomed = aFromHostRecord->mDoomed;
 }
 
 nsHostRecord::~nsHostRecord()
 {
     Telemetry::Accumulate(Telemetry::DNS_BLACKLIST_COUNT, mBlacklistedCount);
     delete addr_info;
-    delete addr;
 }
 
 bool
 nsHostRecord::Blacklisted(NetAddr *aQuery)
 {
     // must call locked
     LOG(("Checking blacklist for host [%s%s%s], host record [%p].\n",
           LOG_HOST(host, netInterface), this));
@@ -348,17 +347,17 @@ nsHostRecord::SizeOfIncludingThis(Malloc
 
     // The |host| field (inherited from nsHostKey) actually points to extra
     // memory that is allocated beyond the end of the nsHostRecord (see
     // nsHostRecord::Create()).  So it will be included in the
     // |mallocSizeOf(this)| call above.
 
     n += SizeOfResolveHostCallbackListExcludingHead(&callbacks, mallocSizeOf);
     n += addr_info ? addr_info->SizeOfIncludingThis(mallocSizeOf) : 0;
-    n += mallocSizeOf(addr);
+    n += mallocSizeOf(addr.get());
 
     n += mBlacklistedItems.ShallowSizeOfExcludingThis(mallocSizeOf);
     for (size_t i = 0; i < mBlacklistedItems.Length(); i++) {
         n += mBlacklistedItems[i].SizeOfExcludingThisIfUnshared(mallocSizeOf);
     }
     return n;
 }
 
@@ -813,18 +812,18 @@ nsHostResolver::ResolveHost(const char  
             }
             // try parsing the host name as an IP address literal to short
             // circuit full host resolution.  (this is necessary on some
             // platforms like Win9x.  see bug 219376 for more details.)
             else if (PR_StringToNetAddr(host, &tempAddr) == PR_SUCCESS) {
                 LOG(("  Host is IP Literal [%s].\n", host));
                 // ok, just copy the result into the host record, and be done
                 // with it! ;-)
-                he->rec->addr = new NetAddr();
-                PRNetAddrToNetAddr(&tempAddr, he->rec->addr);
+                he->rec->addr = MakeUnique<NetAddr>();
+                PRNetAddrToNetAddr(&tempAddr, he->rec->addr.get());
                 // put reference to host record on stack...
                 Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2,
                                       METHOD_LITERAL);
                 result = he->rec;
             }
             else if (mPendingCount >= MAX_NON_PRIORITY_REQUESTS &&
                      !IsHighPriority(flags) &&
                      !he->rec->resolving) {

--- a/netwerk/dns/nsHostResolver.h
+++ b/netwerk/dns/nsHostResolver.h
@@ -16,16 +16,17 @@
 #include "nsIDNSListener.h"
 #include "nsIDNSService.h"
 #include "nsString.h"
 #include "nsTArray.h"
 #include "GetAddrInfo.h"
 #include "mozilla/net/DNS.h"
 #include "mozilla/net/DashboardTypes.h"
 #include "mozilla/TimeStamp.h"
+#include "mozilla/UniquePtr.h"
 
 class nsHostResolver;
 class nsHostRecord;
 class nsResolveHostCallback;
 
 #define MAX_RESOLVER_THREADS_FOR_ANY_PRIORITY  3
 #define MAX_RESOLVER_THREADS_FOR_HIGH_PRIORITY 5
 #define MAX_NON_PRIORITY_REQUESTS 150
@@ -70,17 +71,17 @@ public:
      * assigned a value.  only the resolver worker thread modifies
      * nsHostRecord (and only in nsHostResolver::OnLookupComplete);
      * the other threads just read it.  therefore the resolver worker
      * thread doesn't need to lock when reading |addr_info|.
      */
     Mutex        addr_info_lock;
     int          addr_info_gencnt; /* generation count of |addr_info| */
     mozilla::net::AddrInfo *addr_info;
-    mozilla::net::NetAddr  *addr;
+    mozilla::UniquePtr<mozilla::net::NetAddr> addr;
     bool         negative;   /* True if this record is a cache of a failed lookup.
                                 Negative cache entries are valid just like any other
                                 (though never for more than 60 seconds), but a use
                                 of that negative entry forces an asynchronous refresh. */
 
     enum ExpirationStatus {
         EXP_VALID,
         EXP_GRACE,