Plumb GrBackendFormat into the GrPrimitiveProcessor::TextureSampler

This is not a substantive CL. It is just setting up for removing the
usage of the GrGpu in the creation of the GrProgramDesc.

Change-Id: Ic24204de256862e5e780626bde3a44f4d735c6e9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/249121
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/gl/GrGLGpuProgramCache.cpp b/src/gpu/gl/GrGLGpuProgramCache.cpp
index 0109741..592605e 100644
--- a/src/gpu/gl/GrGLGpuProgramCache.cpp
+++ b/src/gpu/gl/GrGLGpuProgramCache.cpp
@@ -52,6 +52,7 @@
     // TODO: can this be unified between GL, Vk and Mtl?
     // Get GrGLProgramDesc
     GrProgramDesc desc;
+
     if (!GrProgramDesc::Build(&desc, renderTarget, programInfo, primitiveType, gpu)) {
         GrCapsDebugf(gpu->caps(), "Failed to gl program descriptor!\n");
         return nullptr;