This introduces `PlatformDispatcher.implicitView`, a low-level primitive for the framework's bootstrapping. Most code, including the framework after bootstrapping, will use `View.of(context)` instead of this new API. This new primitive will let us deprecate the `window` global.
Goals:
1. **Enable multi-window**. The `PlatformDispatcher.implicitView` is nullable. If `null`, the app must create a window to get a view it can draw into.
2. **Backwards compatibility**. For "single window" apps, `PlatformDispatcher.instance.implicitView` should behave as similar to `window` as possible.
1. The `PlatformDispatcher.instance.implicitView.viewId` should be `0`.
1. The `PlatformDispatcher.instance.implicitView` must be available synchronously at root isolate startup. This allows the framework to determine if it can make single window assumptions at startup.
2. The `PlatformDispatcher.instance.implicitView` reference must not change after startup: if it is null at startup, it must always be null; if it is non-null at startup, it must always be non-null. If "single window" app enters headless mode, the implicit view must remain non-null.
In the future, the embedder will control whether an implicit view is created: mobile & legacy desktop apps will have an implicit view, multi-window desktop apps won't have an implicit view. This requires updating the engine's embedder API and is out-of-scope for this change. For now, all apps will have an implicit view.
Part of https://github.com/flutter/flutter/issues/120306
This patch also eliminates some extraneous tracing that is happening
every frame. It is possible to get the same trace calls by enabling
the API stream if needed.
Also refactors the NotifyIdle callsites to just always work in
TimeDeltas rather than converting back and forth between them and
TimePoints, which I think reads more clearly.
* Add calls to Dart_NotifyDestroyed when the flutter view is destroyed.
* Add unit test case.
* Format.
* Ensure the destroy task runs.
* Address code review comments.
Update Picture rasterization for toImage to accept a layer tree, optionally flattening on the raster thread if present.
Update Deferred GPU image for toImageSync to accept a layer tree, flattening it the first time it creates an image, storing the resulting display list.
This is also a performance fix for the zoom page transition, which currently does too much work on the UI thread on frame 1
This PR changes how embedder API's SendKeyData sends ui.KeyData to the framework. The packets are now sent over the existing platform messenger, reusing the entirety of its code path and functionalities while keeping the embedder API unchanged
Group together externally-managed UIDartState.
It's a frequent pattern to enable access to shell resources from the
framework via UIDartState. These handles are passed through several
other objects, where they lay mostly dormant. This refactor just aims
to ease maintenance of this state.
UIDartState is essentially just an easy to extend bus for dropping
off the shell kids in UIDartState, with constructors/operators that
remove the need for providing a full initializer lists in unittests.
* Revert "Revert "Set SkPath::setIsVolatile based on whether the path survives at least two frames (#22620)" (#23044)"
This reverts commit feda80cb42f99e2588a9a6b9ab3dd1f812d0f45b.
* Fix tracing
