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

This reverts commit 48825b11ad25c98b9a4884d5cc0edd4e290c4409.

Reason for revert: nanobench

Original change's description:
> Redefine the meaning of sample counts in GPU backend.
> 
> Old: 0  -> nonMSAA
>      1+ -> MSAA
> 
> New:
>      0  -> error/unsupported
>      1  -> nonMSAA
>      2+ -> MSAA
> 
> We still allow 0 to mean nonMSAA in three sets of public APIs for backwards compatibility:
> 
> 1) SkSurface factories
> 2) GrBackendRenderTarget constructors
> 3) GrCaps::getSampleCnt()'s requestedCount parameter
> 
> However, we immediately clamp to 1 and treat 0 as invalid/non-renderable internally.
> 
> This also changes the behavior when using a large sample count. We now fail in that case rather than using the largest sample available sample count. GrCaps::getSampleCount() will return 0 in this case.
> 
> 
> Bug: skia:
> Change-Id: Ida22c6b22c1365e563c9046b611e88bf5eb3ff33
> Reviewed-on: https://skia-review.googlesource.com/101560
> Reviewed-by: Greg Daniel <egdaniel@google.com>
> Commit-Queue: Brian Salomon <bsalomon@google.com>

TBR=egdaniel@google.com,bsalomon@google.com

Change-Id: Ic257619a8a5ee9ac15419ecf10259e42daed7f82
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/102662
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

1 files changed, 3 insertions, 5 deletions

diff --git a/src/gpu/GrTexture.cpp b/src/gpu/GrTexture.cpp
index dd0631775f..b4cefb0174 100644
--- a/src/gpu/GrTexture.cpp
+++ b/src/gpu/GrTexture.cpp
@@ -78,7 +78,7 @@ bool GrTexture::StealBackendTexture(sk_sp<GrTexture>&& texture,
 
 void GrTexture::computeScratchKey(GrScratchKey* key) const {
     const GrRenderTarget* rt = this->asRenderTarget();
-    int sampleCount = 1;
+    int sampleCount = 0;
     if (rt) {
         sampleCount = rt->numStencilSamples();
     }
@@ -92,10 +92,8 @@ void GrTexturePriv::ComputeScratchKey(GrPixelConfig config, int width, int heigh
                                       GrMipMapped mipMapped, GrScratchKey* key) {
     static const GrScratchKey::ResourceType kType = GrScratchKey::GenerateResourceType();
     uint32_t flags = isRenderTarget;
-    SkASSERT(width > 0);
-    SkASSERT(height > 0);
-    SkASSERT(sampleCnt > 0);
-    SkASSERT(1 == sampleCnt || isRenderTarget);
+
+    SkASSERT(0 == sampleCnt || isRenderTarget);
 
     // make sure desc.fConfig fits in 5 bits
     SkASSERT(sk_float_log2(kLast_GrPixelConfig) <= 5);