Windows Store certification requires that the application trim its graphics resources on suspend. There are at least two ways to do this:
1. Add an extension to ANGLE to return the DXGIDevice from eglQuerySurfacePointerANGLE. Then get the device pointer and call Trim() inside the winrt QPA plugin.
2. Add a suspending callback inside ANGLE, and call Trim() there.
The downsides of the approach #1 are that it requires more than one patch, and that it requires the platform plugin to link to DXGI. The downsides of approach #2 are that it is introduces another fairly invasive patch to ANGLE, and that the developer has no control over Trim() being called (or not called).