Implement UI hit testing + Reticle scaling

chrome/browser/android/vr_shell/vr_shell.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_VR_SHELL_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_H_
 
 #include <jni.h>
 #include <memory>
 #include <vector>
@@ skipping 87 matching lines @@
   std::unique_ptr<gvr::BufferViewport> buffer_viewport_;
   std::unique_ptr<gvr::SwapChain> swap_chain_;
 
   gvr::Mat4f view_matrix_;
   gvr::Mat4f projection_matrix_;
 
   gvr::Mat4f head_pose_;
   gvr::Vec3f forward_vector_;
 
   gvr::Sizei render_size_;
+  float cursor_distance_;
 
   std::unique_ptr<VrCompositor> content_compositor_view_;
   content::ContentViewCore* content_cvc_;
 
   std::unique_ptr<VrShellRenderer> vr_shell_renderer_;
   base::android::ScopedJavaGlobalRef<jobject> j_vr_shell_;
 
   gvr::Quatf controller_quat_;
   bool controller_active_ = false;
   gvr::Vec3f look_at_vector_;
 
   bool webvr_mode_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(VrShell);
 };
 
 bool RegisterVrShell(JNIEnv* env);
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_H_