[vr] Add a frame rate counter for the vr UI

chrome/browser/android/vr_shell/vr_shell_gl.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_GL_H_
 #define CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_GL_H_
 
 #include <memory>
 #include <queue>
 #include <utility>
@@ skipping 25 matching lines @@
 class ScopedJavaSurface;
 class SurfaceTexture;
 }
 
 namespace gpu {
 struct MailboxHolder;
 }
 
 namespace vr_shell {
 
+class FPSMeter;
 class MailboxToSurfaceBridge;
 class UiScene;
 class VrController;
 class VrShell;
 class VrShellRenderer;
 struct ContentRectangle;
 
 struct WebVrBounds {
   WebVrBounds(gvr::Rectf left, gvr::Rectf right, gvr::Sizei size)
       : left_bounds(left), right_bounds(right), source_size(size) {}
@@ skipping 176 matching lines @@
   base::WeakPtr<VrShell> weak_vr_shell_;
   scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner_;
 
   uint8_t frame_index_ = 0;
   // Larger than frame_index_ so it can be initialized out-of-band.
   uint16_t last_frame_index_ = -1;
 
   // Attributes for gesture detection while holding app button.
   gvr::Vec3f controller_start_direction_;
 
+  std::unique_ptr<FPSMeter> fps_meter_;
+
   base::WeakPtrFactory<VrShellGl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(VrShellGl);
 };
 
 }  // namespace vr_shell
 
 #endif  // CHROME_BROWSER_ANDROID_VR_SHELL_VR_SHELL_GL_H_