create struct to hold all the params passed around for shader::context

src/effects/SkPerlinNoiseShader.cpp

Index: src/effects/SkPerlinNoiseShader.cpp
diff --git a/src/effects/SkPerlinNoiseShader.cpp b/src/effects/SkPerlinNoiseShader.cpp
index 5adb582506e807830c2fcfff9c7c71654406ade7..a4944fb8ffdd2efd59d4d54de94aba20aa4e8865 100644
--- a/src/effects/SkPerlinNoiseShader.cpp
+++ b/src/effects/SkPerlinNoiseShader.cpp
@@ -425,13 +425,12 @@ SkPMColor SkPerlinNoiseShader::PerlinNoiseShaderContext::shade(
     return SkPreMultiplyARGB(rgba[3], rgba[0], rgba[1], rgba[2]);
 }
 
-SkShader::Context* SkPerlinNoiseShader::createContext(const SkBitmap& device, const SkPaint& paint,
-                                                      const SkMatrix& matrix, void* storage) const {
-    if (!this->validContext(device, paint, matrix)) {
+SkShader::Context* SkPerlinNoiseShader::createContext(const ContextRec& rec, void* storage) const {
+    if (!this->validContext(rec)) {
         return NULL;
     }
 
-    return SkNEW_PLACEMENT_ARGS(storage, PerlinNoiseShaderContext, (*this, device, paint, matrix));
+    return SkNEW_PLACEMENT_ARGS(storage, PerlinNoiseShaderContext, (*this, rec));
 }
 
 size_t SkPerlinNoiseShader::contextSize() const {
@@ -439,11 +438,10 @@ size_t SkPerlinNoiseShader::contextSize() const {
 }
 
 SkPerlinNoiseShader::PerlinNoiseShaderContext::PerlinNoiseShaderContext(
-        const SkPerlinNoiseShader& shader, const SkBitmap& device,
-        const SkPaint& paint, const SkMatrix& matrix)
-    : INHERITED(shader, device, paint, matrix)
+        const SkPerlinNoiseShader& shader, const ContextRec& rec)
+    : INHERITED(shader, rec)
 {
-    SkMatrix newMatrix = matrix;
+    SkMatrix newMatrix = *rec.fMatrix;
     newMatrix.postConcat(shader.getLocalMatrix());
     SkMatrix invMatrix;
     if (!newMatrix.invert(&invMatrix)) {