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

chrome/browser/ui/views/pip/pip_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_PIP_PIP_WINDOW_VIEWS_H_
+#define CHROME_BROWSER_UI_VIEWS_PIP_PIP_WINDOW_VIEWS_H_
+
+#include "chrome/browser/ui/pip/pip_window.h"
+#include "ui/views/widget/widget.h"
+
+// The Views window for Picture in Picture.
+class PipWindowViews : public PipWindow {
+ public:
+  PipWindowViews();
+  ~PipWindowViews() override;
+
+  void Init() override;
+  ui::Layer* GetLayer() override;
+
+  // ui::BaseWindow:
+  bool IsActive() const override;
+  bool IsMaximized() const override;
+  bool IsMinimized() const override;
+  bool IsFullscreen() const override;
+  gfx::NativeWindow GetNativeWindow() const override;
+  gfx::Rect GetRestoredBounds() const override;
+  ui::WindowShowState GetRestoredState() const override;
+  gfx::Rect GetBounds() const override;
+  void Show() override;
+  void Hide() override;
+  void ShowInactive() override;
+  void Close() override;
+  void Activate() override;
+  void Deactivate() override;
+  void Maximize() override;
+  void Minimize() override;
+  void Restore() override;
+  void SetBounds(const gfx::Rect& bounds) override;
+  void FlashFrame(bool flash) override;
+  bool IsAlwaysOnTop() const override;
+  void SetAlwaysOnTop(bool always_on_top) override;
+
+ private:
+  views::Widget* widget_;
+
+  DISALLOW_COPY_AND_ASSIGN(PipWindowViews);
+};
+
+#endif  // CHROME_BROWSER_UI_VIEWS_PIP_PIP_WINDOW_VIEWS_H_