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

chrome/browser/android/vr_shell/vr_shell_gl.cc

 // 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.
 
 #include "chrome/browser/android/vr_shell/vr_shell_gl.h"
 
 #include <chrono>
 #include <limits>
 #include <utility>
 
 #include "base/android/jni_android.h"
 #include "base/callback_helpers.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/threading/thread_task_runner_handle.h"
+#include "chrome/browser/android/vr_shell/fps_meter.h"
 #include "chrome/browser/android/vr_shell/mailbox_to_surface_bridge.h"
 #include "chrome/browser/android/vr_shell/ui_elements.h"
 #include "chrome/browser/android/vr_shell/ui_interface.h"
 #include "chrome/browser/android/vr_shell/ui_scene.h"
 #include "chrome/browser/android/vr_shell/vr_controller.h"
 #include "chrome/browser/android/vr_shell/vr_gl_util.h"
 #include "chrome/browser/android/vr_shell/vr_math.h"
 #include "chrome/browser/android/vr_shell/vr_shell.h"
 #include "chrome/browser/android/vr_shell/vr_shell_renderer.h"
 #include "device/vr/android/gvr/gvr_delegate.h"
@@ skipping 114 matching lines @@
     scoped_refptr<base::SingleThreadTaskRunner> main_thread_task_runner,
     gvr_context* gvr_api,
     bool initially_web_vr,
     bool reprojected_rendering)
     : web_vr_mode_(initially_web_vr),
       surfaceless_rendering_(reprojected_rendering),
       task_runner_(base::ThreadTaskRunnerHandle::Get()),
       binding_(this),
       weak_vr_shell_(weak_vr_shell),
       main_thread_task_runner_(std::move(main_thread_task_runner)),
+#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)

[mthiesse, 2017/04/12 02:39:00]

Oops, I meant to suggest DCHECK_IS_ON. Then you don't need to check two flags.

+      fps_meter_(new FPSMeter()),
+#endif
       weak_ptr_factory_(this) {
   GvrInit(gvr_api);
 }
 
 VrShellGl::~VrShellGl() {
   vsync_task_.Cancel();
   // TODO(mthiesse): Can we omit the Close() here? Concern is that if
   // both ends of the connection ever live in the same process for
   // some reason, we could receive another VSync request in response
   // to the closing message in the destructor but fail to respond to
@@ skipping 669 matching lines @@
     TRACE_EVENT0("gpu", "VrShellGl::Submit");
     frame.Submit(*buffer_viewport_list_, head_pose);
   }
 
   // No need to swap buffers for surfaceless rendering.
   if (!surfaceless_rendering_) {
     // TODO(mthiesse): Support asynchronous SwapBuffers.
     TRACE_EVENT0("gpu", "VrShellGl::SwapBuffers");
     surface_->SwapBuffers();
   }
+
+#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
+  // After saving the timestamp, fps will be available via GetFPS().
+  // TODO(vollick): enable rendering of this framerate in a HUD.
+  fps_meter_->AddFrame(current_time);
+  LOG(ERROR) << "fps: " << fps_meter_->GetFPS();
+#endif
 }
 
 void VrShellGl::DrawWorldElements(const gvr::Mat4f& head_pose) {
   TRACE_EVENT0("gpu", "VrShellGl::DrawWorldElements");
 
   if (ShouldDrawWebVr()) {
     // WebVR is incompatible with 3D world compositing since the
     // depth buffer was already populated with unknown scaling - the
     // WebVR app has full control over zNear/zFar. Just leave the
     // existing content in place in the primary buffer without
@@ skipping 427 matching lines @@
   // InitializeGl. Revisit if the initialization order changes.
   device::mojom::VRDisplayInfoPtr info =
       device::GvrDelegate::CreateVRDisplayInfo(gvr_api_.get(),
                                                webvr_surface_size_, device_id);
   main_thread_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&RunVRDisplayInfoCallback, callback, base::Passed(&info)));
 }
 
 }  // namespace vr_shell