Add passive and FOV-locked properties to UI elements.

chrome/browser/resources/vr_shell/vr_shell_ui_api.js

Index: chrome/browser/resources/vr_shell/vr_shell_ui_api.js
diff --git a/chrome/browser/resources/vr_shell/vr_shell_ui_api.js b/chrome/browser/resources/vr_shell/vr_shell_ui_api.js
index 018972ccaf2c5f26f42f6162a2d85d8080b07aba..d1fdb00323078b387e35ae2a2e3749c15f56b100 100644
--- a/chrome/browser/resources/vr_shell/vr_shell_ui_api.js
+++ b/chrome/browser/resources/vr_shell/vr_shell_ui_api.js
@@ -162,6 +162,21 @@ var api = (function() {
     setVisible(visible) {
       this.visible = !!visible;
     }
+
+    /**
+     * Passive implies that an element ignores input, even if visible.
+     */
+    setPassive(passive) {
+      this.passive = !!passive;
+    }
+
+    /**
+     * Causes an element to be rendered relative to the field of view, rather
+     * than the scene.  Elements locked in this way should not have a parent.
+     */
+    setLockToFieldOfView(locked) {
+      this.lockToFov = !!locked;
+    }
   };
 
   /**