VR: Add a loading indicator to the scene.

chrome/browser/android/vr_shell/ui_elements/ui_element.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 205 matching lines @@
     return inheritable_transform_;
   }
   void set_inheritable_transform(const Transform& transform) {
     inheritable_transform_ = transform;
   }
 
   // A flag usable during transformation calculates to avoid duplicate work.
   bool dirty() const { return dirty_; }
   void set_dirty(bool dirty) { dirty_ = dirty; }
 
+  // By default, sets an element to be visible or not. This may be overridden to
+  // allow finer control of element visibility.
+  virtual void SetEnabled(bool enabled);
+
  private:
   // Valid IDs are non-negative.
   int id_ = -1;
 
   // If a non-negative parent ID is specified, applicable transformations
   // are applied relative to the parent, rather than absolutely.
   int parent_id_ = -1;
 
   // If true, this object will be visible.
   bool visible_ = true;
@@ skipping 52 matching lines @@
   bool dirty_ = false;
 
   Transform transform_;
 
   DISALLOW_COPY_AND_ASSIGN(UiElement);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_UI_ELEMENTS_UI_ELEMENT_H_