Add Subscribers to Passphrase

Summary: Fixes T9078, Adds SubscribableInterface to Passphrase.

Test Plan: Create a new passphrase, see myself subscribed. Subscribe to other Passphrases.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T9078

Differential Revision: https://secure.phabricator.com/D13799

src/__phutil_library_map__.php

@@ -5189,6 +5189,7 @@ phutil_register_library_map(array(
       'PhabricatorApplicationTransactionInterface',
       'PhabricatorPolicyInterface',
       'PhabricatorFlaggableInterface',
+      'PhabricatorSubscribableInterface',
       'PhabricatorDestructibleInterface',
       'PhabricatorSpacesInterface',
     ),

src/applications/passphrase/controller/PassphraseCredentialViewController.php

@@ -193,6 +193,8 @@ final class PassphraseCredentialViewController extends PassphraseController {
         $viewer->renderHandleList($used_by_phids));
     }
 
+    $properties->invokeWillRenderEvent();
+
     $description = $credential->getDescription();
     if (strlen($description)) {
       $properties->addSectionHeader(

src/applications/passphrase/storage/PassphraseCredential.php

@@ -5,6 +5,7 @@ final class PassphraseCredential extends PassphraseDAO
     PhabricatorApplicationTransactionInterface,
     PhabricatorPolicyInterface,
     PhabricatorFlaggableInterface,
+    PhabricatorSubscribableInterface,
     PhabricatorDestructibleInterface,
     PhabricatorSpacesInterface {
 
@@ -147,6 +148,23 @@ final class PassphraseCredential extends PassphraseDAO
     return null;
   }
 
+
+/* -(  PhabricatorSubscribableInterface  )----------------------------------- */
+
+
+  public function isAutomaticallySubscribed($phid) {
+    return false;
+  }
+
+  public function shouldShowSubscribersProperty() {
+    return true;
+  }
+
+  public function shouldAllowSubscription($phid) {
+    return true;
+  }
+
+
 /* -(  PhabricatorDestructibleInterface  )----------------------------------- */
 
   public function destroyObjectPermanently(