Hide Audit comment table reads behind an API

Summary: Ref T4896. Buries all direct access to the table so we can limit the surface area affected by the migration.

Test Plan:
  - Grepped for `PhabricatorAuditComment`.
  - Grepped for `audit_comment`.
  - Viewed a bunch of comments.
  - Added a comment.
  - Reindexed a commit.
  - Searched for unique term in new comment.

Reviewers: btrahan, joshuaspence

Reviewed By: joshuaspence

Subscribers: epriestley

Maniphest Tasks: T4896

Differential Revision: https://secure.phabricator.com/D10019

src/applications/audit/editor/PhabricatorAuditCommentEditor.php

@@ -40,8 +40,8 @@ final class PhabricatorAuditCommentEditor extends PhabricatorEditor {
     $commit = $this->commit;
     $actor = $this->getActor();
 
-    $other_comments = id(new PhabricatorAuditComment())->loadAllWhere(
-      'targetPHID = %s',
+    $other_comments = PhabricatorAuditComment::loadComments(
+      $actor,
       $commit->getPHID());
 
     $inline_comments = array();

src/applications/audit/storage/PhabricatorAuditComment.php

@@ -15,6 +15,15 @@ final class PhabricatorAuditComment extends PhabricatorAuditDAO
   protected $content;
   protected $metadata = array();
 
+  public static function loadComments(
+    PhabricatorUser $viewer,
+    $commit_phid) {
+
+    return id(new PhabricatorAuditComment())->loadAllWhere(
+      'targetPHID = %s',
+      $commit_phid);
+  }
+
   public function getConfiguration() {
     return array(
       self::CONFIG_SERIALIZATION => array(

src/applications/diffusion/controller/DiffusionCommitController.php

@@ -643,8 +643,8 @@ final class DiffusionCommitController extends DiffusionController {
 
   private function buildComments(PhabricatorRepositoryCommit $commit) {
     $user = $this->getRequest()->getUser();
-    $comments = id(new PhabricatorAuditComment())->loadAllWhere(
-      'targetPHID = %s ORDER BY dateCreated ASC',
+    $comments = PhabricatorAuditComment::loadComments(
+      $user,
       $commit->getPHID());
 
     $inlines = PhabricatorAuditInlineComment::loadPublishedComments(

src/applications/repository/search/PhabricatorRepositoryCommitSearchIndexer.php

@@ -66,8 +66,8 @@ final class PhabricatorRepositoryCommitSearchIndexer
       PhabricatorRepositoryRepositoryPHIDType::TYPECONST,
       $date_created);
 
-    $comments = id(new PhabricatorAuditComment())->loadAllWhere(
-      'targetPHID = %s',
+    $comments = PhabricatorAuditComment::loadComments(
+      $this->getViewer(),
       $commit->getPHID());
     foreach ($comments as $comment) {
       if (strlen($comment->getContent())) {