Allow VRDisplay to specify which frame the layer bounds should be updated at.

chrome/browser/android/vr_shell/non_presenting_gvr_delegate.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/non_presenting_gvr_delegate.h"
 
 #include "chrome/browser/android/vr_shell/vr_shell.h"
 
 namespace vr_shell {
 
@@ skipping 35 matching lines @@
   StartVSyncLoop();
 }
 
 void NonPresentingGvrDelegate::OnSwitchToPresentingDelegate() {
   StopVSyncLoop();
 }
 
 void NonPresentingGvrDelegate::StopVSyncLoop() {
   vsync_task_.Cancel();
   if (!callback_.is_null())
-    callback_.Run(nullptr, 0);
+    callback_.Run(nullptr, 0, -1);
   callback_.Reset();
   if (binding_.is_bound())
     binding_.Close();
   gvr_api_->PauseTracking();
   paused_ = false;
 }
 
 void NonPresentingGvrDelegate::StartVSyncLoop() {
   vsync_task_.Reset(
       base::Bind(&NonPresentingGvrDelegate::OnVSync, base::Unretained(this)));
@@ skipping 16 matching lines @@
   target = now + vsync_interval_;
   int64_t intervals = (target - vsync_timebase_) / vsync_interval_;
   target = vsync_timebase_ + intervals * vsync_interval_;
   if (!vsync_task_.IsCancelled()) {
     task_runner_->PostDelayedTask(FROM_HERE, vsync_task_.callback(),
                                   target - now);
   }
 
   double time = (intervals * vsync_interval_).InSecondsF();
   if (!callback_.is_null()) {
-    callback_.Run(GetPose(), time);
-    callback_.Reset();
+    SendVSync(time, std::move(callback_));
   } else {
     pending_vsync_ = true;
     pending_time_ = time;
   }
 }
 
 void NonPresentingGvrDelegate::GetVSync(const GetVSyncCallback& callback) {
   if (!pending_vsync_) {
     callback_ = std::move(callback);
     return;
   }
   pending_vsync_ = false;
-  callback.Run(GetPose(), pending_time_);
+  SendVSync(pending_time_, std::move(callback));
 }
 
 void NonPresentingGvrDelegate::UpdateVSyncInterval(long timebase_nanos,
                                                    double interval_seconds) {
   vsync_timebase_ = base::TimeTicks();
   vsync_timebase_ += base::TimeDelta::FromMicroseconds(timebase_nanos / 1000);
   vsync_interval_ = base::TimeDelta::FromSecondsD(interval_seconds);
   StartVSyncLoop();
 }
 
-device::mojom::VRPosePtr NonPresentingGvrDelegate::GetPose() {
+void NonPresentingGvrDelegate::SendVSync(double time,
+                                         GetVSyncCallback callback) {
   gvr::ClockTimePoint target_time = gvr::GvrApi::GetTimePointNow();
   target_time.monotonic_system_time_nanos += kPredictionTimeWithoutVsyncNanos;
 
-  gvr::Mat4f head_mat =
-      gvr_api_->GetHeadSpaceFromStartSpaceRotation(target_time);
-  head_mat = gvr_api_->ApplyNeckModel(head_mat, 1.0f);
-
-  uint32_t pose_index = pose_index_++;
-
-  return VrShell::VRPosePtrFromGvrPose(head_mat, pose_index);
+  gvr::Mat4f head_mat = gvr_api_->ApplyNeckModel(
+      gvr_api_->GetHeadSpaceFromStartSpaceRotation(target_time), 1.0f);
+  callback.Run(VrShell::VRPosePtrFromGvrPose(head_mat), time, -1);
 }
 
 }  // namespace vr_shell