Update to new SkRuntimeEffect main() signature

The color filters used for exotic color space conversion in
skia_renderer are built on SkRuntimeEffect. The required signature
for main() in the SkSL has changed, this just adapts to the new
signature and semantics.

Bug: skia:10613
Change-Id: I031cbd597810ec9629b3308db4548c5842b0b5de
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2375932Reviewed-by: ccameron <ccameron@chromium.org>
Commit-Queue: Brian Osman <brianosman@google.com>
Cr-Commit-Position: refs/heads/master@{#801749}

components/viz/service/display/skia_renderer.cc

@@ -2265,8 +2265,10 @@ sk_sp<SkColorFilter> SkiaRenderer::GetColorSpaceConversionFilter(
     const char* hdr = R"(
 uniform half offset;
 uniform half multiplier;
+in shader child;
 
-void main(inout half4 color) {
+half4 main() {
+  half4 color = sample(child);
   // un-premultiply alpha
   if (color.a > 0)
     color.rgb /= color.a;
@@ -2277,6 +2279,7 @@ void main(inout half4 color) {
     const char* ftr = R"(
   // premultiply alpha
   color.rgb *= color.a;
+  return color;
 }
 )";
 
@@ -2292,7 +2295,8 @@ void main(inout half4 color) {
   input.multiplier = resource_multiplier;
   sk_sp<SkData> data = SkData::MakeWithCopy(&input, sizeof(input));
 
-  return effect->makeColorFilter(std::move(data));
+  sk_sp<SkColorFilter> child = nullptr;  // = default input color
+  return effect->makeColorFilter(std::move(data), &child, 1);
 }
 
 sk_sp<SkColorFilter> SkiaRenderer::GetContentColorFilter() {

skia/config/SkUserConfig.h

@@ -225,9 +225,6 @@ SK_API void SkDebugf_FileLine(const char* file,
 #define SK_SUPPORT_LEGACY_AAA_CHOICE
 #endif
 
-// Staging for changes to SkRuntimeEffect main() signature
-#define SK_USE_LEGACY_RUNTIME_EFFECT_SIGNATURE
-
 // Staging for lowp::bilerp_clamp_8888, and for planned misc. others.
 #define SK_DISABLE_LOWP_BILERP_CLAMP_CLAMP_STAGE
 

ui/gfx/color_transform_unittest.cc

@@ -519,8 +519,11 @@ TEST(SimpleColorSpace, CanParseSkShaderSource) {
     for (const auto& dst : common_color_spaces) {
       auto transform = ColorTransform::NewColorTransform(
           src, dst, ColorTransform::Intent::INTENT_PERCEPTUAL);
-      std::string source = "void main(inout half4 color) {" +
-                           transform->GetSkShaderSource() + "}";
+      std::string source =
+          "in shader child;\n"
+          "half4 main() {\n"
+          "  half4 color = sample(child);\n" +
+          transform->GetSkShaderSource() + " return color; }";
       auto result =
           SkRuntimeEffect::Make(SkString(source.c_str(), source.length()));
       EXPECT_NE(std::get<0>(result), nullptr);