Change how the VR reticle distance is determined.

chrome/browser/resources/vr_shell/vr_shell_ui_scene.js

Index: chrome/browser/resources/vr_shell/vr_shell_ui_scene.js
diff --git a/chrome/browser/resources/vr_shell/vr_shell_ui_scene.js b/chrome/browser/resources/vr_shell/vr_shell_ui_scene.js
index d1651a56f04ed41c054a3d62d9ac52991ad8c0f7..56e36978583515e843c2910db0f9e4ea035d64b5 100644
--- a/chrome/browser/resources/vr_shell/vr_shell_ui_scene.js
+++ b/chrome/browser/resources/vr_shell/vr_shell_ui_scene.js
@@ -129,12 +129,26 @@ scene.Scene = class {
     delete this.animations[id];
   }
 
+  /**
+   * Set the background color of the scene.
+   * @param {{r: number, b: number, g: number, a: number}} color

[cjgrant, 2017/02/16 22:53:39]

Note that this works, for future reference.  If the UI's color parameters were
passed in as {a, b, c, x}, this will fail closure.

+   */
   setBackgroundColor(color) {
     this.commands.push(
         {'type': api.Command.UPDATE_BACKGROUND, 'data': {'color': color}});
   }
 
   /**
+   * Set the radius of background-bounding sphere.
+   * @param {number} distance
+   */
+  setBackgroundDistance(distance) {
+    this.commands.push({
+      'type': api.Command.UPDATE_BACKGROUND,
+      'data': {'distance': distance}
+    });
+  }
+  /**
    * Purge all elements in the scene.
    */
   purge() {