Make cache RRect blur masks with exact fit textures.

I made this be kApprox here:
https://skia-review.googlesource.com/c/skia/+/264838

to resolve a TODO. However, it uses more memory and after thinking about
it I'm not sure why it was a TODO to use an approximate texture for a
cached texture. If it's worth caching it's probably worth making a trim
texture.

Bug: chromium:1044017

Change-Id: Iac8302291592231875f5619b33e8ee6e13a92a64
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/267444
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/effects/GrRRectBlurEffect.fp b/src/gpu/effects/GrRRectBlurEffect.fp
index 0d6a2b7..a0ac5e7 100644
--- a/src/gpu/effects/GrRRectBlurEffect.fp
+++ b/src/gpu/effects/GrRRectBlurEffect.fp
@@ -53,7 +53,7 @@
                 key, GrColorType::kAlpha_8, kBottomLeft_GrSurfaceOrigin));
         if (!mask) {
             auto rtc = GrRenderTargetContext::MakeWithFallback(
-                    context, GrColorType::kAlpha_8, nullptr, SkBackingFit::kApprox, dimensions);
+                    context, GrColorType::kAlpha_8, nullptr, SkBackingFit::kExact, dimensions);
             if (!rtc) {
                 return nullptr;
             }
diff --git a/src/gpu/effects/generated/GrRRectBlurEffect.h b/src/gpu/effects/generated/GrRRectBlurEffect.h
index 2ebf6bc..2c72a45 100644
--- a/src/gpu/effects/generated/GrRRectBlurEffect.h
+++ b/src/gpu/effects/generated/GrRRectBlurEffect.h
@@ -55,7 +55,7 @@
                 key, GrColorType::kAlpha_8, kBottomLeft_GrSurfaceOrigin));
         if (!mask) {
             auto rtc = GrRenderTargetContext::MakeWithFallback(
-                    context, GrColorType::kAlpha_8, nullptr, SkBackingFit::kApprox, dimensions);
+                    context, GrColorType::kAlpha_8, nullptr, SkBackingFit::kExact, dimensions);
             if (!rtc) {
                 return nullptr;
             }