When there are no more platform views, make sure the overlay layer is
hidden. When a platform view is added again, show the overlay. The
show/hide allows us to avoid continually recreating and destroying the
overlay surface + swapchain when a platform view slides in and out of
frame.
To further reduce memory usage, we could do a delayed de-allocation of
the overlay layer (say after 50 frames of no platform view, destroy it).
But I'm leaving this to a follow up.
Developers will need to _conditionally_ use HCPP (or the framework will
need to handle it automatically). This requires the ability to query at
runtime whether HCPP mode is enabled + supported.
Add a message channel to do so, and add the usage of this to the
android_engine_test. Does not yet add any automatic selection.
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Co-authored-by: Matan Lurey <matanlurey@users.noreply.github.com>
Use the PlatformViewController2 to register a platform view, allow the
dart side platform view logic to opt into this new platform view. Wires
up an integration test with android_engine_test.
