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

shell/browser/native_window.h
virtual void SetEscapeTouchBarItem(gin_helper::PersistentDictionary item);
  
  virtual void SelectPreviousTab();
  virtual void SelectNextTab();
  virtual void MergeAllWindows();
  virtual void MoveTabToNewWindow();
  virtual void ToggleTabBar();
  virtual bool AddTabbedWindow(NativeWindow* window);
  
  virtual bool SetWindowButtonVisibility(bool visible);
  
  virtual void SetAutoHideMenuBar(bool auto_hide);
  virtual bool IsMenuBarAutoHide();
  virtual void SetMenuBarVisibility(bool visible);
  virtual bool IsMenuBarVisible();
  
  double GetAspectRatio();
  gfx::Size GetAspectRatioExtraSize();
  virtual void SetAspectRatio(double aspect_ratio, const gfx::Size& extra_size);
  
  virtual void PreviewFile(const std::string& path,
                           const std::string& display_name);
  virtual void CloseFilePreview();
  virtual void SetGTKDarkThemeEnabled(bool use_dark_theme) = 0;
  
  virtual gfx::Rect ContentBoundsToWindowBounds(
      const gfx::Rect& bounds) const = 0;
  virtual gfx::Rect WindowBoundsToContentBounds(
      const gfx::Rect& bounds) const = 0;
  base::WeakPtr<NativeWindow> GetWeakPtr() {