Initialize RenderWidget(Host)(View)s with correct visibility state

content/renderer/render_process_visibility_manager.cc

-// Copyright 2013 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 "content/renderer/render_process_visibility_manager.h"
-
-#include "base/logging.h"
-#include "base/memory/memory_pressure_listener.h"
-
-namespace content {
-
-RenderProcessVisibilityManager::RenderProcessVisibilityManager()
-    : num_visible_render_widgets_(0) {
-}
-
-RenderProcessVisibilityManager::~RenderProcessVisibilityManager() {
-}
-
-// static
-RenderProcessVisibilityManager* RenderProcessVisibilityManager::GetInstance() {
-  return Singleton<RenderProcessVisibilityManager>::get();
-}
-
-void RenderProcessVisibilityManager::WidgetVisibilityChanged(bool visible) {
-#if !defined(SYSTEM_NATIVELY_SIGNALS_MEMORY_PRESSURE)
-  num_visible_render_widgets_ += visible ? 1 : -1;
-  DCHECK_LE(0, num_visible_render_widgets_);
-  if (num_visible_render_widgets_ == 0) {
-    // TODO(vollick): Remove this this heavy-handed approach once we're polling
-    // the real system memory pressure.
-    base::MemoryPressureListener::NotifyMemoryPressure(
-        base::MemoryPressureListener::MEMORY_PRESSURE_MODERATE);
-  }
-#endif
-}
-
-}  // namespace content