Bug 1688833 - Migrate LookupForAdd to WithEntryHandle in modules/libpref. r=KrisWright

Differential Revision: https://phabricator.services.mozilla.com/D104196

modules/libpref/Preferences.cpp

@@ -2607,21 +2607,21 @@ nsPrefBranch::AddObserverImpl(const nsACString& aDomain, nsIObserver* aObserver,
     pCallback = new PrefCallback(prefName, aObserver, this);
   }
 
-  auto p = mObservers.LookupForAdd(pCallback);
-  if (p) {
-    NS_WARNING("Ignoring duplicate observer.");
-    delete pCallback;
-    return NS_OK;
-  }
+  mObservers.WithEntryHandle(pCallback, [&](auto&& p) {
+    if (p) {
+      NS_WARNING("Ignoring duplicate observer.");
+      delete pCallback;
+    } else {
+      p.Insert(pCallback);
 
-  p.OrInsert([&pCallback]() { return pCallback; });
-
-  // We must pass a fully qualified preference name to the callback
-  // aDomain == nullptr is the only possible failure, and we trapped it with
-  // NS_ENSURE_ARG above.
-  Preferences::RegisterCallback(NotifyObserver, prefName, pCallback,
-                                Preferences::PrefixMatch,
-                                /* isPriority */ false);
+      // We must pass a fully qualified preference name to the callback
+      // aDomain == nullptr is the only possible failure, and we trapped it with
+      // NS_ENSURE_ARG above.
+      Preferences::RegisterCallback(NotifyObserver, prefName, pCallback,
+                                    Preferences::PrefixMatch,
+                                    /* isPriority */ false);
+    }
+  });
 
   return NS_OK;
 }

modules/libpref/SharedPrefMap.h

@@ -638,11 +638,11 @@ class MOZ_RAII SharedPrefMapBuilder {
     ValueIdx Add(const ValueType& aDefaultValue) {
       auto index = uint16_t(mDefaultEntries.Count());
 
-      auto entry = mDefaultEntries.LookupForAdd(aDefaultValue).OrInsert([&]() {
-        return Entry{index, false, aDefaultValue};
-      });
+      return mDefaultEntries.WithEntryHandle(aDefaultValue, [&](auto&& entry) {
+        entry.OrInsertWith([&] { return Entry{index, false, aDefaultValue}; });
 
-      return {entry.mIndex, false};
+        return ValueIdx{entry.Data().mIndex, false};
+      });
     }
 
     // Adds an entry for a preference with a user value to the array. Regardless