WebVR: process animations from posted task to yield for other events

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 <limits>
 #include <utility>
 
 #include "base/android/jni_android.h"
@@ skipping 1217 matching lines @@
   main_thread_task_runner_->PostTask(
       FROM_HERE, base::Bind(&VrShell::ForceExitVr, weak_vr_shell_));
 }
 
 void VrShellGl::UpdateScene(std::unique_ptr<base::ListValue> commands) {
   scene_->HandleCommands(std::move(commands), TimeInMicroseconds());
 }
 
 void VrShellGl::SendVSync(base::TimeDelta time,
                           const GetVSyncCallback& callback) {
-  TRACE_EVENT0("input", "VrShellGl::SendVSync");
+  uint8_t frame_index = frame_index_++;
 
-  uint8_t frame_index = frame_index_++;
+  TRACE_EVENT1("input", "VrShellGl::SendVSync", "frame", frame_index);
 
   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);
 
   webvr_head_pose_[frame_index % kPoseRingBufferSize] = head_mat;
 
@@ skipping 15 matching lines @@
   // appropriate recommended render resolution as the default size during
   // InitializeGl. Revisit if the initialization order changes.
   device::mojom::VRDisplayInfoPtr info = VrShell::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