Add SlidingAverage to FPSMeter, use for WebVR prediction time

device/vr/android/gvr/gvr_delegate.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 DEVICE_VR_ANDROID_GVR_DELEGATE_H
 #define DEVICE_VR_ANDROID_GVR_DELEGATE_H
 
 #include <stdint.h>
 
 #include "device/vr/vr_export.h"
 #include "device/vr/vr_service.mojom.h"
 #include "device/vr/vr_types.h"
 #include "gpu/command_buffer/common/mailbox_holder.h"
 #include "third_party/gvr-android-sdk/src/libraries/headers/vr/gvr/capi/include/gvr_types.h"
 
 namespace gvr {
 class GvrApi;
 }
 
 namespace device {
 
 class DEVICE_VR_EXPORT GvrDelegate {
  public:
   static mojom::VRPosePtr VRPosePtrFromGvrPose(const vr::Mat4f& head_mat);
+  static void GetGvrPoseWithNeckModel(gvr::GvrApi* gvr_api,
+                                      vr::Mat4f* out,
+                                      int64_t prediction_time);
   static void GetGvrPoseWithNeckModel(gvr::GvrApi* gvr_api, vr::Mat4f* out);
   static mojom::VRPosePtr GetVRPosePtrWithNeckModel(gvr::GvrApi* gvr_api,
+                                                    vr::Mat4f* head_mat_out,
+                                                    int64_t prediction_time);
+  static mojom::VRPosePtr GetVRPosePtrWithNeckModel(gvr::GvrApi* gvr_api,
                                                     vr::Mat4f* head_mat_out);
   static gfx::Size GetRecommendedWebVrSize(gvr::GvrApi* gvr_api);
   static mojom::VRDisplayInfoPtr CreateVRDisplayInfo(gvr::GvrApi* gvr_api,
                                                      gfx::Size recommended_size,
                                                      uint32_t device_id);
 
   virtual void SetWebVRSecureOrigin(bool secure_origin) = 0;
   virtual void SubmitWebVRFrame(int16_t frame_index,
                                 const gpu::MailboxHolder& mailbox) = 0;
   virtual void UpdateWebVRTextureBounds(int16_t frame_index,
@@ skipping 15 matching lines @@
 // GvrDelegate, which allows WebVR presentation.
 class DEVICE_VR_EXPORT PresentingGvrDelegate : public GvrDelegate {
  public:
   virtual void SetSubmitClient(
       device::mojom::VRSubmitFrameClientPtr submit_client) = 0;
 };
 
 }  // namespace device
 
 #endif  // DEVICE_VR_ANDROID_GVR_DELEGATE_H