SkSL GLSL generator writes default precision for sampler2D/samplerExternalOS/sampler2DRect

This is a stop gap. We should probably base the precision decision on the texture format.

Also removes all code used to add sampler precision to program keys. The precision that
was added to the key did not affect the generated GLSL.

Bug: skia:8863
Bug: skia:6718
Change-Id: Ibdb702e1aca5d48d83e2f24cb24010a0b7270871
Reviewed-by: Ethan Nicholas <>
Commit-Queue: Brian Salomon <>
15 files changed