Revert "Revert "Redefine the meaning of sample counts in GPU backend.""

Fixes gpu config default samples to be 1 and updates config parsing test accordingly.

This reverts commit c1ce2f7966babaae0deb150f93f1227ee5af9285.

Bug: skia:
Change-Id: I456973b1f52ced85a2011ea10fc49449bfc5846f
Reviewed-on: https://skia-review.googlesource.com/102147
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/GrBackendTextureImageGenerator.cpp b/src/gpu/GrBackendTextureImageGenerator.cpp
index ae27912..af28409 100644
--- a/src/gpu/GrBackendTextureImageGenerator.cpp
+++ b/src/gpu/GrBackendTextureImageGenerator.cpp
@@ -186,8 +186,8 @@
         GrMipMapped mipMapped = willNeedMipMaps ? GrMipMapped::kYes : GrMipMapped::kNo;
 
         sk_sp<GrRenderTargetContext> rtContext(context->makeDeferredRenderTargetContext(
-                SkBackingFit::kExact, info.width(), info.height(), proxy->config(), nullptr,
-                0, mipMapped, proxy->origin(), nullptr, SkBudgeted::kYes));
+                SkBackingFit::kExact, info.width(), info.height(), proxy->config(), nullptr, 1,
+                mipMapped, proxy->origin(), nullptr, SkBudgeted::kYes));
 
         if (!rtContext) {
             return nullptr;