Improve UI and documentation for "Ignore Attributes" in Owners slightly

Summary:
See PHI251. Ref T13137.

- Replace the perplexing text box with a checkbox that explains what it does.
- Mention this feature in the documentation.

Test Plan:
- Clicked/unclicked checkbox.
- Read documentation.
- Used an existing checkbox control in Slowvote to make sure I didn't break it.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13137

Differential Revision: https://secure.phabricator.com/D19433

src/__phutil_library_map__.php

···
     'PhabricatorChatLogDAO' => 'applications/chatlog/storage/PhabricatorChatLogDAO.php',
     'PhabricatorChatLogEvent' => 'applications/chatlog/storage/PhabricatorChatLogEvent.php',
     'PhabricatorChatLogQuery' => 'applications/chatlog/query/PhabricatorChatLogQuery.php',
+    'PhabricatorCheckboxesEditField' => 'applications/transactions/editfield/PhabricatorCheckboxesEditField.php',
     'PhabricatorChunkedFileStorageEngine' => 'applications/files/engine/PhabricatorChunkedFileStorageEngine.php',
     'PhabricatorClassConfigType' => 'applications/config/type/PhabricatorClassConfigType.php',
     'PhabricatorClusterConfigOptions' => 'applications/config/option/PhabricatorClusterConfigOptions.php',
···
       'PhabricatorPolicyInterface',
     ),
     'PhabricatorChatLogQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
+    'PhabricatorCheckboxesEditField' => 'PhabricatorEditField',
     'PhabricatorChunkedFileStorageEngine' => 'PhabricatorFileStorageEngine',
     'PhabricatorClassConfigType' => 'PhabricatorTextConfigType',
     'PhabricatorClusterConfigOptions' => 'PhabricatorApplicationConfigOptions',

src/applications/owners/editor/PhabricatorOwnersPackageEditEngine.php

···
         ->setIsConduitOnly(true)
         ->setValue($object->getStatus())
         ->setOptions($object->getStatusNameMap()),
-      id(new PhabricatorStringListEditField())
+      id(new PhabricatorCheckboxesEditField())
         ->setKey('ignored')
         ->setLabel(pht('Ignored Attributes'))
         ->setDescription(pht('Ignore paths with any of these attributes.'))
         ->setTransactionType(
           PhabricatorOwnersPackageIgnoredTransaction::TRANSACTIONTYPE)
-        ->setValue(array_keys($object->getIgnoredPathAttributes())),
+        ->setValue(array_keys($object->getIgnoredPathAttributes()))
+        ->setOptions(
+          array(
+            'generated' => pht('Ignore generated files (review only).'),
+          )),
       id(new PhabricatorConduitEditField())
         ->setKey('paths.set')
         ->setLabel(pht('Paths'))

src/applications/transactions/editfield/PhabricatorCheckboxesEditField.php

···
+<?php
+
+final class PhabricatorCheckboxesEditField
+  extends PhabricatorEditField {
+
+  private $options;
+
+  protected function newControl() {
+    $options = $this->getOptions();
+
+    return id(new AphrontFormCheckboxControl())
+      ->setOptions($options);
+  }
+
+  protected function newConduitParameterType() {
+    return new ConduitStringListParameterType();
+  }
+
+  protected function newHTTPParameterType() {
+    return new AphrontStringListHTTPParameterType();
+  }
+
+  public function setOptions(array $options) {
+    $this->options = $options;
+    return $this;
+  }
+
+  public function getOptions() {
+    if ($this->options === null) {
+      throw new PhutilInvalidStateException('setOptions');
+    }
+
+    return $this->options;
+  }
+
+}

src/docs/user/userguide/owners.diviner

···
 write more sophisticated rules.
 
 
+Ignored Attributes
+==================
+
+You can automatically exclude certain types of files, like generated files,
+with **Ignored Attributes**.
+
+When a package is marked as ignoring files with a particular attribute, and
+a file in a particular change has that attribute, the file will be ignored when
+computing ownership.
+
+(This feature is currently rough, only works for Differential revisions, and
+may not always compute the correct set of owning packages in some complex
+cases where it interacts with dominion rules.)
+
+
 Files in Multiple Packages
 ==========================
 

src/view/form/control/AphrontFormCheckboxControl.php

···
     return 'aphront-form-control-checkbox';
   }
 
+  public function setOptions(array $options) {
+    $boxes = array();
+    foreach ($options as $key => $value) {
+      $boxes[] = array(
+        'value' => $key,
+        'label' => $value,
+      );
+    }
+
+    $this->boxes = $boxes;
+
+    return $this;
+  }
+
   protected function renderInput() {
     $rows = array();
     foreach ($this->boxes as $box) {
···
       if ($id === null) {
         $id = celerity_generate_unique_node_id();
       }
+
+      $name = idx($box, 'name');
+      if ($name === null) {
+        $name = $this->getName().'[]';
+      }
+
+      $value = $box['value'];
+
+      if (array_key_exists('checked', $box)) {
+        $checked = $box['checked'];
+      } else {
+        $checked = in_array($value, $this->getValue());
+      }
+
       $checkbox = phutil_tag(
         'input',
         array(
           'id' => $id,
           'type' => 'checkbox',
-          'name' => $box['name'],
+          'name' => $name,
           'value' => $box['value'],
-          'checked' => $box['checked'] ? 'checked' : null,
+          'checked' => $checked ? 'checked' : null,
           'disabled' => $this->getDisabled() ? 'disabled' : null,
         ));
       $label = phutil_tag(