Don't draw the task graph line image on devices by default

Summary:
See downstream <https://phabricator.wikimedia.org/T210482>.

On mobile, the task graph can take up most of the screen. Hide it on devices. Keep it on the standalone view if you're really dedicated and willing to rotate your phone or whatever to see the lines.

Test Plan: Dragged window real narrow, saw graph hide.

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D20313

src/applications/maniphest/controller/ManiphestTaskGraphController.php

@@ -30,6 +30,7 @@ final class ManiphestTaskGraphController
       ->setViewer($viewer)
       ->setSeedPHID($task->getPHID())
       ->setLimit($graph_limit)
+      ->setIsStandalone(true)
       ->loadGraph();
     if (!$task_graph->isEmpty()) {
       $parent_type = ManiphestTaskDependedOnByTaskEdgeType::EDGECONST;

src/infrastructure/graph/ManiphestTaskGraph.php

@@ -4,6 +4,7 @@ final class ManiphestTaskGraph
   extends PhabricatorObjectGraph {
 
   private $seedMaps = array();
+  private $isStandalone;
 
   protected function getEdgeTypes() {
     return array(
@@ -24,6 +25,15 @@ final class ManiphestTaskGraph
     return $object->isClosed();
   }
 
+  public function setIsStandalone($is_standalone) {
+    $this->isStandalone = $is_standalone;
+    return $this;
+  }
+
+  public function getIsStandalone() {
+    return $this->isStandalone;
+  }
+
   protected function newTableRow($phid, $object, $trace) {
     $viewer = $this->getViewer();
 
@@ -132,6 +142,14 @@ final class ManiphestTaskGraph
         array(
           true,
           !$this->getRenderOnlyAdjacentNodes(),
+        ))
+      ->setDeviceVisibility(
+        array(
+          true,
+
+          // On mobile, we only show the actual graph drawing if we're on the
+          // standalone page, since it can take over the screen otherwise.
+          $this->getIsStandalone(),
         ));
   }