<!--  As an open source project with a dedicated but small maintainer team, it can sometimes take a long time for issues to be addressed so please be patient and we will get back to you as soon as we can.
-->

### Preflight Checklist
<!-- Please ensure you've completed the following steps by replacing [ ] with [x]-->

* [x] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
* [x] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
* [x] I have searched the issue tracker for a feature request that matches the one I want to file, without success.

### Problem Description
<!-- Is your feature request related to a problem? Please add a clear and concise description of what the problem is. -->

BrowserWindow currently offers "moved" event related to moving a window, but it only has "will-resize" and "resize" events. I want to save the current dimensions of a window when its size changes, but "will-resize" and "resize" events get fired at every single pixel change. This results in an unnecessarily large number of saving function calls or a need for debouncing the event.

### Proposed Solution
<!-- Describe the solution you'd like in a clear and concise manner -->

Adding "resized" event to BrowserWindow will solve the problem stated above.

### Alternatives Considered
<!-- A clear and concise description of any alternative solutions or features you've considered. -->

### Additional Information
<!-- Add any other context about the problem here. -->

shell/browser/native_window.h
virtual void Minimize() = 0;
  virtual void Restore() = 0;
  virtual bool IsMinimized() = 0;
  virtual void SetFullScreen(bool fullscreen) = 0;
  virtual bool IsFullscreen() const = 0;
  virtual void SetBounds(const gfx::Rect& bounds, bool animate = false) = 0;
  virtual gfx::Rect GetBounds() = 0;
  virtual void SetSize(const gfx::Size& size, bool animate = false);
  virtual gfx::Size GetSize();
  virtual void SetPosition(const gfx::Point& position, bool animate = false);
  virtual gfx::Point GetPosition();
  virtual void SetContentSize(const gfx::Size& size, bool animate = false);
  virtual gfx::Size GetContentSize();
  virtual void SetContentBounds(const gfx::Rect& bounds, bool animate = false);
  virtual gfx::Rect GetContentBounds();
  virtual bool IsNormal();
  virtual gfx::Rect GetNormalBounds() = 0;
  virtual void SetSizeConstraints(
      const extensions::SizeConstraints& size_constraints);
  virtual extensions::SizeConstraints GetSizeConstraints() const;
  virtual void SetContentSizeConstraints(
      const extensions::SizeConstraints& size_constraints);
  virtual extensions::SizeConstraints GetContentSizeConstraints() const;
  virtual void SetMinimumSize(const gfx::Size& size);
  virtual gfx::Size GetMinimumSize() const;
  virtual void SetMaximumSize(const gfx::Size& size);
  virtual gfx::Size GetMaximumSize() const;
  virtual gfx::Size GetContentMinimumSize() const;
  virtual gfx::Size GetContentMaximumSize() const;
  virtual void SetSheetOffset(const double offsetX, const double offsetY);