VR: Add a loading indicator to the scene.

chrome/browser/android/vr_shell/ui_elements/loading_indicator.cc

+// Copyright 2017 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_elements/loading_indicator.h"
+
+#include "base/memory/ptr_util.h"
+#include "chrome/browser/android/vr_shell/textures/loading_indicator_texture.h"
+
+namespace vr_shell {
+
+namespace {
+
+static constexpr int kVisibilityTimeoutMs = 200;
+}
+
+LoadingIndicator::LoadingIndicator(int preferred_width)
+    : TexturedElement(preferred_width),
+      texture_(base::MakeUnique<LoadingIndicatorTexture>()) {}
+
+LoadingIndicator::~LoadingIndicator() = default;
+
+UiTexture* LoadingIndicator::GetTexture() const {
+  return texture_.get();
+}
+
+void LoadingIndicator::SetEnabled(bool enabled) {
+  if (enabled_ == enabled)
+    return;
+  enabled_ = enabled;
+  ResetVisibilityTimer();
+  SetVisibility();
+}
+
+void LoadingIndicator::SetLoading(bool loading) {
+  if (loading_ == loading)
+    return;
+  loading_ = loading;
+  texture_->SetLoading(loading);
+  texture_->SetLoadProgress(0);
+  ResetVisibilityTimer();
+  SetVisibility();
+}
+
+void LoadingIndicator::SetLoadProgress(float progress) {
+  texture_->SetLoadProgress(progress);
+}
+
+void LoadingIndicator::ResetVisibilityTimer() {
+  if (enabled_ && !loading_) {
+    visibility_timer_.Start(
+        FROM_HERE, base::TimeDelta::FromMilliseconds(kVisibilityTimeoutMs),
+        this, &LoadingIndicator::SetVisibility);
+  } else {
+    visibility_timer_.Stop();
+  }
+}
+
+void LoadingIndicator::SetVisibility() {
+  set_visible(enabled_ && (loading_ || visibility_timer_.IsRunning()));
+}
+
+void LoadingIndicator::OnBeginFrame(const base::TimeTicks& ticks) {
+  if (enabled_ && texture_->dirty())
+    UpdateTexture();
+}
+
+}  // namespace vr_shell