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

extensions/common/permissions/settings_override_permission.cc

Index: extensions/common/permissions/settings_override_permission.cc
diff --git a/extensions/common/permissions/settings_override_permission.cc b/extensions/common/permissions/settings_override_permission.cc
index e23bc2eecc5c2e4fed369d9fc02ccadbba87001e..3a8d838a480ee8b91a4838b46936b8de89f3a2c7 100644
--- a/extensions/common/permissions/settings_override_permission.cc
+++ b/extensions/common/permissions/settings_override_permission.cc
@@ -50,7 +50,7 @@ PermissionMessages SettingsOverrideAPIPermission::GetMessages() const {
 
 bool SettingsOverrideAPIPermission::Check(
     const APIPermission::CheckParam* param) const {
-  return (param == NULL);
+  return (param == nullptr);
 }
 
 bool SettingsOverrideAPIPermission::Contains(const APIPermission* rhs) const {
@@ -68,7 +68,7 @@ bool SettingsOverrideAPIPermission::FromValue(
     const base::Value* value,
     std::string* /*error*/,
     std::vector<std::string>* unhandled_permissions) {
-  return (value == NULL);
+  return (value == nullptr);
 }
 
 scoped_ptr<base::Value> SettingsOverrideAPIPermission::ToValue() const {
@@ -82,7 +82,7 @@ APIPermission* SettingsOverrideAPIPermission::Clone() const {
 APIPermission* SettingsOverrideAPIPermission::Diff(
     const APIPermission* rhs) const {
   CHECK_EQ(info(), rhs->info());
-  return NULL;
+  return nullptr;
 }
 
 APIPermission* SettingsOverrideAPIPermission::Union(