enforce 16byte alignment in shader contexts

src/effects/SkPerlinNoiseShader.cpp

Index: src/effects/SkPerlinNoiseShader.cpp
diff --git a/src/effects/SkPerlinNoiseShader.cpp b/src/effects/SkPerlinNoiseShader.cpp
index ed7340ca3ae15c67e066f1526ef3674397b7bc9d..a32d8ac2bb62340b5e846d4ff7b6165a7870c2e3 100644
--- a/src/effects/SkPerlinNoiseShader.cpp
+++ b/src/effects/SkPerlinNoiseShader.cpp
@@ -434,8 +434,8 @@ SkShader::Context* SkPerlinNoiseShader::onCreateContext(const ContextRec& rec,
     return new (storage) PerlinNoiseShaderContext(*this, rec);
 }
 
-size_t SkPerlinNoiseShader::contextSize(const ContextRec&) const {
-    return sizeof(PerlinNoiseShaderContext);
+size_t SkPerlinNoiseShader::onContextSize(const ContextRec&) const {
+    return SkAlign16(sizeof(PerlinNoiseShaderContext));
 }
 
 SkPerlinNoiseShader::PerlinNoiseShaderContext::PerlinNoiseShaderContext(