Add ContextRec param to SkShader::contextSize()

src/core/SkEmptyShader.h

Index: src/core/SkEmptyShader.h
diff --git a/src/core/SkEmptyShader.h b/src/core/SkEmptyShader.h
index 6453e0e4400b880fd3256dfb585ca71877326ec8..c1713d1a2ee91e7a4bbabcaed144589911d4c204 100644
--- a/src/core/SkEmptyShader.h
+++ b/src/core/SkEmptyShader.h
@@ -20,7 +20,7 @@ class SK_API SkEmptyShader : public SkShader {
 public:
     SkEmptyShader() {}
 
-    size_t contextSize() const override {
+    size_t contextSize(const ContextRec&) const override {
         // Even though createContext returns nullptr we have to return a value of at least
         // sizeof(SkShader::Context) to satisfy SkSmallAllocator.
         return sizeof(SkShader::Context);