Description of Change

Fixes #48589.
Fixes #48588.

Background reading for maintainers: https://electronhq.slack.com/docs/T394SAQKC/F09ME0YPPV1.

This PR affects Linux environments which use CSD on Wayland. Today that means mostly just GNOME, but in the near future it will include frameless windows on any desktop environment. I regularized bounds handling and fixed edge cases to ensure:

• Windows are created at the exact size requested by the user, both with and without without content sizing.
• Windows can be resized accurately with setBounds/SetSize/setContentSize (if the compositor supports this).
• BrowserWindow.getBounds reports the logical size of the window, without leaking invisible decoration insets
• Windows first appear in the center of the screen instead of the top left corner.
• Windows preserve their expected bounds across minimize, maximize, restoring, tiling, etc., without shrinking or flickering or suddenly "jumping" to a new size on focus changes or when the resize handle is grabbed.
• Min and max sizes are respected (with one edge case for max size that will require a separate Chromium patch).

e.g.: A window created at 800x600 on GNOME will now visually measure 800x600 including the titlebar, just like on other platforms, and getBounds will report 800x600. If the window is created with useContentSize: true, it will visually measure something like 800x650, with an 800x600 content area. Bounds will be stable throughout the window lifecycle, and future bounds operations will work consistently and as expected.

Thought process

When CSD is in use, Chromium's accelerated widget is larger than the visible window frame. An 800x600 window might be inset into an 844x844 widget, with the outer part being used for shadows and resize targets. Electron is now aware of this possibility and has tools to manage it consistently.

Stabilizing CSD bounds fixes a large class of interaction quirks on Wayland which were caused by the compositor fighting with Electron over confcliting size constraints.It is also a necessary pre-req to introduce shadows to frameless windows: #48570. (Some of this PR anticipates that upcoming work by hoisting shared methods into FramelessView.)

The bulk of the PR is about adding awareness of the difference between the window's "logical bounds" and the total "widget bounds" to native_window_views. This code is used on both Linux and Windows, and I tried to keep the logic as platform-independent as possible, both to avoid ifdefs, but also because Windows also has similar issues with resize target bounds that extend past the logical/client area which these interfaces may be able to help with in the future.

In general, Electron should now be able to handle "widgets that are larger than the actually visible window/frame" as a platform-independent problem, whenever it comes up. At a high level, the philosophy here is:

• Public bounds APIs (setBounds, getBounds and derivatives) deal in logical geometric bounds instead of the total bounds of the accelerated widget. These APIs always strip out/convert invisible insets used by the widget for shadows, decorations, and resize targets.
• FramelessView impls control how this conversion works according to their platform-specific needs. The base case is that they have 0-width insets, so logical bounds are equivalent to widget bounds.
• Callers can still operate on the widget() directly if they need to manipulate or read the total underlying bounds.

So there is some more internal complexity to negotiate the difference between logical and widget bounds spaces, but most callers should only care about logical bounds, especially in APIs exposed to JS.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• relevant API documentation, tutorials, and examples are updated and follow the documentation style guide
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fixed several issues with consistent window sizing and resizing on Linux when CSD is in use (e.g. on GNOME/Wayland) and added support for creating content-sized windows.