Re-land "converted OverdrawColorFilter to SkSL"

This reverts commit 2d3cac58fcc8f2d398a421b0341c36479a6ba324.

Bug: skia:
Change-Id: I6607d419f6b30c3e17b52ec5ce67d489bd1ad1dc
Reviewed-on: https://skia-review.googlesource.com/64080
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
diff --git a/src/sksl/SkSLCPPCodeGenerator.h b/src/sksl/SkSLCPPCodeGenerator.h
index 2766522..77331da 100644
--- a/src/sksl/SkSLCPPCodeGenerator.h
+++ b/src/sksl/SkSLCPPCodeGenerator.h
@@ -62,7 +62,7 @@
     void addUniform(const Variable& var);
 
     // writes a printf escape that will be filled in at runtime by the given C++ expression string
-    void writeRuntimeValue(const Type& type, const String& cppCode);
+    void writeRuntimeValue(const Type& type, const Layout& layout, const String& cppCode);
 
     void writeVarInitializer(const Variable& var, const Expression& value) override;