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

chrome/browser/ui/pip/pip_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_PIP_PIP_WINDOW_H_
+#define CHROME_BROWSER_UI_PIP_PIP_WINDOW_H_
+
+#include "ui/base/base_window.h"
+#include "ui/compositor/layer.h"
+
+class PipWindow : public ui::BaseWindow {

[mlamouri (slow - plz ping), 2017/06/05 13:09:33]

Name: what about PictureInPictureWindow? It's a mouthful but I'm afraid "Pip"
might be unclear for most.

[apacible, 2017/06/13 07:58:08]

See other comment on naming.

+ public:
+  PipWindow() {}
+  virtual ~PipWindow() {}

[mlamouri (slow - plz ping), 2017/06/05 13:09:33]

Aren't you missing the implementation file?

Also, would be better to move definition there.

[apacible, 2017/06/13 07:58:08]

It's implemented in pip_window_views.cc/h. The Mac version would be a
*cocoa.h/mm file.

+
+  // Returns a created PipWindow. This is defined in the platform-specific
+  // implementation for the class.
+  static std::unique_ptr<PipWindow> Create();

[mlamouri (slow - plz ping), 2017/06/05 13:09:33]

What's the difference between ::Create() and the ctor if both are public?

[apacible, 2017/06/13 07:58:08]

This is implemented on the platform-class level, which creates the corresponding
views or cocoa Window. This follows the pattern currently used for other UI
elements with different platform implementations.

+
+  virtual void Init() = 0;
+  virtual ui::Layer* GetLayer() = 0;
+
+  // 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:
+  DISALLOW_COPY_AND_ASSIGN(PipWindow);
+};
+
+#endif  // CHROME_BROWSER_UI_PIP_PIP_WINDOW_H_