Use transactions to apply Ajax settings mutations

Summary:
Ref T4103. Some settings (mostly nav collapsed/expanded states) use this endpoint to make adjustments when users press keys (like `\` to toggle the durable column).

All of these settings are now formal, so swap things over to transactions.

Test Plan: Collapsed/expanded various navs, reloaded pages, settings stuck.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T4103

Differential Revision: https://secure.phabricator.com/D16035

src/applications/settings/controller/PhabricatorSettingsAdjustController.php

@@ -4,13 +4,23 @@ final class PhabricatorSettingsAdjustController
   extends PhabricatorController {
 
   public function handleRequest(AphrontRequest $request) {
-    $user = $request->getUser();
+    $viewer = $this->getViewer();
 
-    $prefs = $user->loadPreferences();
-    $prefs->setPreference(
-      $request->getStr('key'),
-      $request->getStr('value'));
-    $prefs->save();
+    $preferences = PhabricatorUserPreferences::loadUserPreferences($viewer);
+
+    $editor = id(new PhabricatorUserPreferencesEditor())
+      ->setActor($viewer)
+      ->setContentSourceFromRequest($request)
+      ->setContinueOnNoEffect(true)
+      ->setContinueOnMissingFields(true);
+
+    $key = $request->getStr('key');
+    $value = $request->getStr('value');
+
+    $xactions = array();
+    $xactions[] = $preferences->newTransaction($key, $value);
+
+    $editor->applyTransactions($preferences, $xactions);
 
     return id(new AphrontAjaxResponse())->setContent(array());
   }