[graphite] Remove DepthStencilOnly handling

I believe this was only needed during the sprint, before we had
RenderSteps.

Bug: skia:12701
Change-Id: I4945fc69f9c1cd419b8c3143b6638e4769761ff9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/541976
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>

include/gpu/graphite/Context.h

@@ -37,7 +37,6 @@ class TextureInfo;
 
 struct ShaderCombo {
     enum class ShaderType {
-        kNone, // does not modify color buffer, e.g. depth and/or stencil only
         kSolidColor,
         kLinearGradient,
         kRadialGradient,

src/core/SkBuiltInCodeSnippetID.h

@@ -12,10 +12,6 @@
 
 // TODO: this needs to be expanded into a more flexible dictionary (esp. for user-supplied SkSL)
 enum class SkBuiltInCodeSnippetID : uint8_t {
-    // TODO: It seems like this requires some refinement. Fundamentally this doesn't seem like a
-    // draw that originated from a PaintParams.
-    kDepthStencilOnlyDraw,
-
     // This isn't just a signal for a failure during paintparams key creation. It also actually
     // implements the default behavior for an erroneous draw. Currently it just draws solid
     // magenta.

src/core/SkKeyHelpers.cpp

@@ -29,6 +29,7 @@ constexpr SkPMColor4f kErrorColor = { 1, 0, 0, 1 };
 
 namespace {
 
+#ifdef SK_GRAPHITE_ENABLED
 // This can be used to catch errors in blocks that have a fixed, known block data size
 void validate_block_header(const SkPaintParamsKeyBuilder* builder,
                            SkBuiltInCodeSnippetID codeSnippetID,
@@ -39,26 +40,10 @@ void validate_block_header(const SkPaintParamsKeyBuilder* builder,
     SkASSERT(builder->byte(headerOffset+SkPaintParamsKey::kBlockSizeOffsetInBytes) ==
              fullBlockSize);
 }
+#endif
 
 } // anonymous namespace
 
-//--------------------------------------------------------------------------------------------------
-namespace DepthStencilOnlyBlock {
-
-static const int kBlockDataSize = 0;
-
-void AddToKey(const SkKeyContext& /* keyContext */,
-              SkPaintParamsKeyBuilder* builder,
-              SkPipelineDataGatherer* /* gatherer */) {
-    builder->beginBlock(SkBuiltInCodeSnippetID::kDepthStencilOnlyDraw);
-    builder->endBlock();
-
-    validate_block_header(builder,
-                          SkBuiltInCodeSnippetID::kDepthStencilOnlyDraw,
-                          kBlockDataSize);
-}
-
-} // namespace DepthStencilOnlyBlock
 
 //--------------------------------------------------------------------------------------------------
 namespace SolidColorShaderBlock {
@@ -689,9 +674,6 @@ SkUniquePaintParamsID CreateKey(const SkKeyContext& keyContext,
     SkDEBUGCODE(builder->checkReset());
 
     switch (s) {
-        case skgpu::graphite::ShaderCombo::ShaderType::kNone:
-            DepthStencilOnlyBlock::AddToKey(keyContext, builder, nullptr);
-            break;
         case skgpu::graphite::ShaderCombo::ShaderType::kSolidColor:
             SolidColorShaderBlock::AddToKey(keyContext, builder, nullptr, kErrorColor);
             break;

src/core/SkShaderCodeDictionary.cpp

@@ -711,16 +711,6 @@ SkShaderCodeDictionary::SkShaderCodeDictionary() {
     // The 0th index is reserved as invalid
     fEntryVector.push_back(nullptr);
 
-    fBuiltInCodeSnippets[(int) SkBuiltInCodeSnippetID::kDepthStencilOnlyDraw] = {
-            "DepthStencil",
-            { },     // no uniforms
-            SnippetRequirementFlags::kNone,
-            { },     // no samplers
-            kErrorName,
-            GenerateDefaultGlueCode,
-            kNoChildren,
-            {}
-    };
     fBuiltInCodeSnippets[(int) SkBuiltInCodeSnippetID::kError] = {
             "Error",
             { },     // no uniforms

tests/graphite/UniformTest.cpp

@@ -37,9 +37,6 @@ std::tuple<SkPaint, int> create_paint(ShaderCombo::ShaderType shaderType,
     sk_sp<SkShader> s;
     int numTextures = 0;
     switch (shaderType) {
-        case ShaderCombo::ShaderType::kNone:
-            SkDEBUGFAIL("kNone cannot be represented as an SkPaint");
-            break;
         case ShaderCombo::ShaderType::kSolidColor:
             break;
         case ShaderCombo::ShaderType::kLinearGradient: