Simplify view getters on GrTextureProducer.

The only thing that affects the view returned is whether it ought to
be MIP mapped or not. So don't take a whole GrSamplerState.

The view() function won't ever change the colortype so just query
GrTextureProducer rather than having view() return a tuple.

The rest is transitively reaching through callers and callees of
GrTextureProducer::view() to only pass filter or GrMipMapped instead of
GrSamplerState. Also, some params that indicate whether MIPs are
requested are changed from bool to GrMipMapped. And some minor style
stuff (mainly de-yoda-ifying GrMipMapped checks, using
GrSurfaceProxyView operator bool()).

Change-Id: Ia184aa793cf51d42642ea3bb0521ce06da2efb10
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/274205
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/src/gpu/GrBlurUtils.cpp b/src/gpu/GrBlurUtils.cpp
index 1ce1e82..cfd9657 100644
--- a/src/gpu/GrBlurUtils.cpp
+++ b/src/gpu/GrBlurUtils.cpp
@@ -153,7 +153,7 @@
 
         GrBitmapTextureMaker maker(context, bm, GrBitmapTextureMaker::Cached::kNo,
                                    SkBackingFit::kApprox);
-        std::tie(filteredMaskView, std::ignore) = maker.view(GrMipMapped::kNo);
+        filteredMaskView = maker.view(GrMipMapped::kNo);
         if (!filteredMaskView.proxy()) {
             return false;
         }