Chromium already includes the necessary plumbing to manage the
visibility properties and `visibilitychange` event so this gets rid of
most of our custom logic for `BrowserWindow` and `BrowserView`.
Note that `webview` remains unchanged and is still affected by the issues
listed below.
User facing changes:
- The `document` visibility properties and `visibilitychange` event are
now also updated/fired in response to occlusion changes on macOS. In
other words, `document.visibilityState` will now be `hidden` on macOS
if the window is occluded by another window.
- Previously, `visibilitychange` was also fired by *both* Electron and
Chromium in some cases (e.g. when hiding the window). Now it is only
fired by Chromium so you no longer get duplicate events.
- The visiblity state of `BrowserWindow`s created with `{ show: false }`
is now initially `visible` until the window is shown and hidden.
- The visibility state of `BrowserWindow`s with `backgroundThrottling`
disabled is now permanently `visible`.
This should also fix#6860 (but not for `webview`).
Right now, `<webview>` is the only way to embed additional content in a
`BrowserWindow`. Unfortunately `<webview>` suffers from a [number of
problems](https://github.com/electron/electron/issues?utf8=%E2%9C%93&q=is%3Aissue%20is%3Aopen%20label%3Awebview%20).
To make matters worse, many of these are upstream Chromium bugs instead
of Electron-specific bugs.
For us at [Figma](https://www.figma.com), the main issue is very slow
performance.
Despite the upstream improvements to `<webview>` through the OOPIF work, it is
probable that there will continue to be `<webview>`-specific bugs in the
future.
Therefore, this introduces a `<webview>` alternative to called `BrowserView`,
which...
- is a thin wrapper around `api::WebContents` (so bugs in `BrowserView` will
likely also be bugs in `BrowserWindow` web contents)
- is instantiated in the main process like `BrowserWindow` (and unlike
`<webview>`, which lives in the DOM of a `BrowserWindow` web contents)
- needs to be added to a `BrowserWindow` to display something on the screen
This implements the most basic API. The API is expected to evolve and change in
the near future and has consequently been marked as experimental. Please do not
use this API in production unless you are prepared to deal with breaking
changes.
In the future, we will want to change the API to support multiple
`BrowserView`s per window. We will also want to consider z-ordering
auto-resizing, and possibly even nested views.
