Restore "Commandeer" action to Differential on EditEngine

Summary:
Ref T11114. This has two pieces of side-effect logic which I've noted locally:

  - Commandeer needs to apply Herald rules.
  - Commandeer needs to move the old author to become a reviewer and remove
    the actor as a reviewer.

Test Plan: Commandeered some revisions.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11114

Differential Revision: https://secure.phabricator.com/D17111

src/__phutil_library_map__.php

@@ -512,6 +512,7 @@ phutil_register_library_map(array(
     'DifferentialRevisionAuthorProjectsHeraldField' => 'applications/differential/herald/DifferentialRevisionAuthorProjectsHeraldField.php',
     'DifferentialRevisionCloseDetailsController' => 'applications/differential/controller/DifferentialRevisionCloseDetailsController.php',
     'DifferentialRevisionCloseTransaction' => 'applications/differential/xaction/DifferentialRevisionCloseTransaction.php',
+    'DifferentialRevisionCommandeerTransaction' => 'applications/differential/xaction/DifferentialRevisionCommandeerTransaction.php',
     'DifferentialRevisionContentAddedHeraldField' => 'applications/differential/herald/DifferentialRevisionContentAddedHeraldField.php',
     'DifferentialRevisionContentHeraldField' => 'applications/differential/herald/DifferentialRevisionContentHeraldField.php',
     'DifferentialRevisionContentRemovedHeraldField' => 'applications/differential/herald/DifferentialRevisionContentRemovedHeraldField.php',
@@ -5185,6 +5186,7 @@ phutil_register_library_map(array(
     'DifferentialRevisionAuthorProjectsHeraldField' => 'DifferentialRevisionHeraldField',
     'DifferentialRevisionCloseDetailsController' => 'DifferentialController',
     'DifferentialRevisionCloseTransaction' => 'DifferentialRevisionActionTransaction',
+    'DifferentialRevisionCommandeerTransaction' => 'DifferentialRevisionActionTransaction',
     'DifferentialRevisionContentAddedHeraldField' => 'DifferentialRevisionHeraldField',
     'DifferentialRevisionContentHeraldField' => 'DifferentialRevisionHeraldField',
     'DifferentialRevisionContentRemovedHeraldField' => 'DifferentialRevisionHeraldField',

src/applications/differential/xaction/DifferentialRevisionCommandeerTransaction.php

@@ -0,0 +1,67 @@
+<?php
+
+final class DifferentialRevisionCommandeerTransaction
+  extends DifferentialRevisionActionTransaction {
+
+  const TRANSACTIONTYPE = 'differential.revision.commandeer';
+  const ACTIONKEY = 'commandeer';
+
+  protected function getRevisionActionLabel() {
+    return pht('Commandeer Revision');
+  }
+
+  protected function getRevisionActionDescription() {
+    return pht('You will take control of this revision and become its author.');
+  }
+
+  public function getIcon() {
+    return 'fa-flag';
+  }
+
+  public function getColor() {
+    return 'sky';
+  }
+
+  public function generateOldValue($object) {
+    return $object->getAuthorPHID();
+  }
+
+  public function generateNewValue($object, $value) {
+    $actor = $this->getActor();
+    return $actor->getPHID();
+  }
+
+  public function applyInternalEffects($object, $value) {
+    $object->setAuthorPHID($value);
+  }
+
+  protected function validateAction($object, PhabricatorUser $viewer) {
+    if ($object->isClosed()) {
+      throw new Exception(
+        pht(
+          'You can not commandeer this revision because it has already '.
+          'been closed. You can only commandeer open revisions.'));
+    }
+
+    if ($this->isViewerRevisionAuthor($object, $viewer)) {
+      throw new Exception(
+        pht(
+          'You can not commandeer this revision because you are already '.
+          'the author.'));
+    }
+  }
+
+  public function getTitle() {
+    return pht(
+      '%s commandeered this revision.',
+      $this->renderAuthor());
+  }
+
+  public function getTitleForFeed() {
+    return pht(
+      '%s commandeered %s.',
+      $this->renderAuthor(),
+      $this->renderObject());
+  }
+
+}