Reland #19396 with a fix for improper scale that was affecting internal tests
Tested: Ran all unittests, ran internal tests, and ran workstation on Fuchsia
BUG: 53062, 53063
The fuchsia code around metrics and sizing was just sending this
information through a side-channel, when the engine already had the
information available. So, delete all of it to make future CLs simpler.
Additionally, the SceneUpdateContext has many unneccesary dependencies
re: metrics and PaintTasks. Break those to make future CLs simpler.
Tested: Ran all unittests and ran workstation on Fuchsia
BUG: 53062, 53063
This is part of a larger effort to expose the difference between GrDirectContext,
which runs on the GPU thread and can directly perform operations like uploading
textures, and GrRecordingContext, which can only queue up work to be delivered
to the GrDirectContext later.
* [fuchsia] Add labels to Scenic nodes.
* [fuchsia] Skip creating Scenic nodes for identity Transforms.
* [fuchsia] Assign elevation to Scenic nodes based on paint order.
* [fuchsia] Create Scenic OpacityNodes at leaf nodes.
* [fuchsia] Composite PhysicalShapeLayers using Skia, except when they need to float above child views.
In that case, they will still need to be pulled
into separate Scenic nodes to be composited on top
of the child view[s].
* [fuchsia] Add tests for Fuchsia-specific layer behavior.
Inspect commands going to Scenic and make sure
they match what is expected.
Also, restructure code to need less member variables,
and other cleanups based on review feedback.
