[OverlayWindow] Add platform-independent window and views implementation.

This change adds a general window that overlays other windows, initially for the use case of picture in picture. This includes a partially stubbed views implementation. Cocoa work will be done in a separate CL.

BUG=726621

Review-Url: https://codereview.chromium.org/2905833004
Cr-Commit-Position: refs/heads/master@{#488150}

chrome/browser/ui/BUILD.gn

@@ -792,6 +792,7 @@ split_static_library("ui") {
       "omnibox/chrome_omnibox_navigation_observer.h",
       "omnibox/clipboard_utils.cc",
       "omnibox/clipboard_utils.h",
+      "overlay/overlay_window.h",
       "page_info/page_info_infobar_delegate.cc",
       "page_info/page_info_infobar_delegate.h",
       "page_info/permission_menu_model.cc",
@@ -1557,6 +1558,8 @@ split_static_library("ui") {
       "views/login_view.h",
       "views/new_back_shortcut_bubble.cc",
       "views/new_back_shortcut_bubble.h",
+      "views/overlay/overlay_window_views.cc",
+      "views/overlay/overlay_window_views.h",
       "views/page_info/chosen_object_row.cc",
       "views/page_info/chosen_object_row.h",
       "views/page_info/chosen_object_row_observer.h",

chrome/browser/ui/overlay/overlay_window.h

+// 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.
+
+#ifndef CHROME_BROWSER_UI_OVERLAY_OVERLAY_WINDOW_H_
+#define CHROME_BROWSER_UI_OVERLAY_OVERLAY_WINDOW_H_
+
+#include "base/memory/ptr_util.h"
+#include "ui/gfx/native_widget_types.h"
+
+namespace gfx {
+class Rect;
+}
+
+namespace ui {
+class Layer;
+}
+
+// This window will always float above other windows. The intention is to show
+// content perpetually while the user is still interacting with the other
+// browser windows.
+class OverlayWindow {
+ public:
+  OverlayWindow() = default;
+  virtual ~OverlayWindow() = default;
+
+  // Returns a created OverlayWindow. This is defined in the platform-specific
+  // implementation for the class.
+  static std::unique_ptr<OverlayWindow> Create();
+
+  virtual void Init() = 0;
+  virtual bool IsActive() const = 0;
+  virtual void Show() = 0;
+  virtual void Hide() = 0;
+  virtual void Close() = 0;
+  virtual void Activate() = 0;
+  virtual bool IsAlwaysOnTop() const = 0;
+  virtual ui::Layer* GetLayer() = 0;
+  virtual gfx::NativeWindow GetNativeWindow() const = 0;
+  // Retrieves the window's current bounds, including its window.
+  virtual gfx::Rect GetBounds() const = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(OverlayWindow);
+};
+
+#endif  // CHROME_BROWSER_UI_OVERLAY_OVERLAY_WINDOW_H_

chrome/browser/ui/views/overlay/overlay_window_views.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/ui/views/overlay/overlay_window_views.h"
+
+#include "ui/views/widget/widget.h"
+
+// static
+std::unique_ptr<OverlayWindow> OverlayWindow::Create() {
+  return base::WrapUnique(new OverlayWindowViews());
+}
+
+OverlayWindowViews::OverlayWindowViews() {
+  widget_.reset(new views::Widget());
+}
+
+OverlayWindowViews::~OverlayWindowViews() = default;
+
+void OverlayWindowViews::Init() {
+  // TODO(apacible): Finalize the type of widget. http://crbug/726621
+  views::Widget::InitParams params(views::Widget::InitParams::TYPE_WINDOW);
+  params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
+
+  // TODO(apacible): Update preferred sizing and positioning.
+  // http://crbug/726621
+  params.bounds = gfx::Rect(200, 200, 700, 500);
+  params.keep_on_top = true;
+  params.visible_on_all_workspaces = true;
+
+  widget_->Init(params);
+  widget_->Show();
+
+  // TODO(apacible): Set the WidgetDelegate for more control over behavior.
+  // http://crbug/726621
+}
+
+bool OverlayWindowViews::IsActive() const {
+  return widget_->IsActive();
+}
+
+void OverlayWindowViews::Show() {
+  widget_->Show();
+}
+
+void OverlayWindowViews::Hide() {
+  widget_->Hide();
+}
+
+void OverlayWindowViews::Close() {
+  widget_->Close();
+}
+
+void OverlayWindowViews::Activate() {
+  widget_->Activate();
+}
+
+bool OverlayWindowViews::IsAlwaysOnTop() const {
+  return true;
+}
+
+ui::Layer* OverlayWindowViews::GetLayer() {
+  return widget_->GetLayer();
+}
+
+gfx::NativeWindow OverlayWindowViews::GetNativeWindow() const {
+  return widget_->GetNativeWindow();
+}
+
+gfx::Rect OverlayWindowViews::GetBounds() const {
+  return widget_->GetRestoredBounds();
+}

chrome/browser/ui/views/overlay/overlay_window_views.h

+// 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.
+
+#ifndef CHROME_BROWSER_UI_VIEWS_OVERLAY_OVERLAY_WINDOW_VIEWS_H_
+#define CHROME_BROWSER_UI_VIEWS_OVERLAY_OVERLAY_WINDOW_VIEWS_H_
+
+#include "chrome/browser/ui/overlay/overlay_window.h"
+
+namespace views {
+class Widget;
+}
+
+// The Views implementation of OverlayWindow.
+class OverlayWindowViews : public OverlayWindow {
+ public:
+  OverlayWindowViews();
+  ~OverlayWindowViews() override;
+
+  // OverlayWindow:
+  void Init() override;
+  bool IsActive() const override;
+  void Show() override;
+  void Hide() override;
+  void Close() override;
+  void Activate() override;
+  bool IsAlwaysOnTop() const override;
+  ui::Layer* GetLayer() override;
+  gfx::NativeWindow GetNativeWindow() const override;
+  gfx::Rect GetBounds() const override;
+
+ private:
+  std::unique_ptr<views::Widget> widget_;
+
+  DISALLOW_COPY_AND_ASSIGN(OverlayWindowViews);
+};
+
+#endif  // CHROME_BROWSER_UI_VIEWS_OVERLAY_OVERLAY_WINDOW_VIEWS_H_