Clean up threading around VR Scene updates.

chrome/browser/android/vr_shell/ui_scene.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/ui_scene.h"
 
 #include "base/values.h"
 #include "chrome/browser/android/vr_shell/animation.h"
 #include "chrome/browser/android/vr_shell/easing.h"
 #include "chrome/browser/android/vr_shell/ui_elements.h"
@@ skipping 260 matching lines @@
   auto& animations = element->animations;
   for (auto it = animations.begin(); it != animations.end(); ++it) {
     const Animation& existing_animation = **it;
     if (existing_animation.id == animation_id) {
       animations.erase(it);
       return;
     }
   }
 }
 
-void UiScene::HandleCommands(const base::ListValue* commands,
+void UiScene::HandleCommands(std::unique_ptr<base::ListValue> commands,
                              int64_t time_in_micro) {
   for (auto& item : *commands) {
     base::DictionaryValue* dict;
     CHECK(item->GetAsDictionary(&dict));
 
     Command type;
     base::DictionaryValue* data;
     CHECK(dict->GetInteger("type", reinterpret_cast<int*>(&type)));
     CHECK(dict->GetDictionary("data", &data));
 
@@ skipping 52 matching lines @@
 
 const std::vector<std::unique_ptr<ContentRectangle>>&
 UiScene::GetUiElements() const {
   return ui_elements_;
 }
 
 UiScene::UiScene() = default;
 
 UiScene::~UiScene() = default;
 
-int64_t UiScene::TimeInMicroseconds() {
-  return std::chrono::duration_cast<std::chrono::microseconds>(
-      std::chrono::steady_clock::now().time_since_epoch()).count();
-}
-
 void UiScene::ApplyRecursiveTransforms(const ContentRectangle& element,
                                        ReversibleTransform* transform) {
   transform->Scale(element.scale.x, element.scale.y, element.scale.z);
   transform->Rotate(element.rotation.x, element.rotation.y,
                     element.rotation.z, element.rotation.angle);
   transform->Translate(element.translation.x, element.translation.y,
                        element.translation.z);
 
   if (element.parent_id >= 0) {
     const ContentRectangle* parent = GetUiElementById(element.parent_id);
@@ skipping 37 matching lines @@
                       reinterpret_cast<int*>(&element->x_anchoring))) {
     CHECK_GE(element->parent_id, 0);
   }
   if (dict.GetInteger("yAnchoring",
                       reinterpret_cast<int*>(&element->y_anchoring))) {
     CHECK_GE(element->parent_id, 0);
   }
 }
 
 }  // namespace vr_shell