Run clang-modernize -use-nullptr over src/extensions/.

extensions/browser/extension_pref_store.cc

Index: extensions/browser/extension_pref_store.cc
diff --git a/extensions/browser/extension_pref_store.cc b/extensions/browser/extension_pref_store.cc
index 3f26cbb3e352787d19c2152d9ae038872198da88..40d1bcf98db229d482ab96edd772ed0f17a8c686 100644
--- a/extensions/browser/extension_pref_store.cc
+++ b/extensions/browser/extension_pref_store.cc
@@ -21,10 +21,8 @@ void ExtensionPrefStore::OnInitializationCompleted() {
 
 void ExtensionPrefStore::OnPrefValueChanged(const std::string& key) {
   CHECK(extension_pref_value_map_);
-  const base::Value *winner =
-      extension_pref_value_map_->GetEffectivePrefValue(key,
-                                                       incognito_pref_store_,
-                                                       NULL);
+  const base::Value* winner = extension_pref_value_map_->GetEffectivePrefValue(
+      key, incognito_pref_store_, nullptr);
   if (winner)
     SetValue(key, winner->DeepCopy());
   else
@@ -34,7 +32,7 @@ void ExtensionPrefStore::OnPrefValueChanged(const std::string& key) {
 void ExtensionPrefStore::OnExtensionPrefValueMapDestruction() {
   CHECK(extension_pref_value_map_);
   extension_pref_value_map_->RemoveObserver(this);
-  extension_pref_value_map_ = NULL;
+  extension_pref_value_map_ = nullptr;
 }
 
 ExtensionPrefStore::~ExtensionPrefStore() {