android: Use UIResource for overscroll glow

ui/base/android/system_ui_resource_manager.cc

+// Copyright 2014 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 "ui/base/android/system_ui_resource_manager.h"
+
+#include "ui/base/android/system_ui_resource_layer.h"
+
+namespace ui {
+
+SystemUIResourceManager::SystemUIResourceManager()
+    : ui_resource_provider_(NULL) {
+}
+
+void SystemUIResourceManager::Subscribe(SystemUIResource::Type type,
+                                        SystemUIResourceLayer* layer) {
+  DCHECK(layer);
+  GetData(type)->Subscribe(layer);
+}
+
+void SystemUIResourceManager::Unsubscribe(SystemUIResource::Type type,
+                                          SystemUIResourceLayer* layer) {
+  DCHECK(layer);
+  GetData(type)->Unsubscribe(layer);
+}
+
+void SystemUIResourceManager::RefreshResourceOnSubscribers(
+    SystemUIResource::Type type) {
+  GetData(type)->RefreshResource();
+}
+
+SystemUIResourceManager::Data* SystemUIResourceManager::GetData(
+    SystemUIResource::Type type) {
+  SystemUIResourceMap::iterator iter = resource_map_.find(type);
+  if (iter == resource_map_.end()) {
+    scoped_ptr<Data> resource_data = make_scoped_ptr(new Data());
+    resource_map_.set(type, resource_data.Pass());
+
+    // Lazily build the resource.
+    BuildResource(type);
+  }
+  return resource_map_.get(type);
+}
+
+UIResourceProvider* SystemUIResourceManager::GetUIResourceProvider() {
+  return ui_resource_provider_;
+}
+
+SystemUIResourceManager::Data::Data() {
+}
+
+SystemUIResourceManager::Data::~Data() {
+  if (resource_)
+    resource_->SetClient(NULL);
+}
+
+void SystemUIResourceManager::Data::Subscribe(SystemUIResourceLayer* layer) {
+  DCHECK(layer);
+  if (resource_)
+    layer->SetUIResourceId(resource_->id());
+
+  if (!subscribers_.HasObserver(layer))
+    subscribers_.AddObserver(layer);
+}
+
+void SystemUIResourceManager::Data::Unsubscribe(SystemUIResourceLayer* layer) {
+  DCHECK(layer);
+  layer->SetUIResourceId(0);
+  subscribers_.RemoveObserver(layer);
+}
+
+void SystemUIResourceManager::Data::SetResource(
+    scoped_ptr<SystemUIResource> resource) {
+  DCHECK(resource);
+  resource_ = resource.Pass();
+  resource_->SetClient(this);
+
+  RefreshResource();
+}
+
+void SystemUIResourceManager::Data::RefreshResource() {
+  if(!resource_)
+    return;
+
+  resource_->Load();
+  FOR_EACH_OBSERVER(
+      SystemUIResourceLayer, subscribers_, SetUIResourceId(resource_->id()));
+}
+
+void SystemUIResourceManager::Data::OnUIResourceIdChanged() {
+  DCHECK(resource_);
+
+  FOR_EACH_OBSERVER(
+      SystemUIResourceLayer, subscribers_, SetUIResourceId(resource_->id()));
+}
+
+} // namespace ui