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

include/effects/SkTransparentShader.h

Index: include/effects/SkTransparentShader.h
diff --git a/include/effects/SkTransparentShader.h b/include/effects/SkTransparentShader.h
index 790e5ae9fd2549c4bc650a333c38492cab13ba50..55513eb53208796f87490a100a5f6d42686bf067 100644
--- a/include/effects/SkTransparentShader.h
+++ b/include/effects/SkTransparentShader.h
@@ -14,15 +14,13 @@ class SK_API SkTransparentShader : public SkShader {
 public:
     SkTransparentShader() {}
 
-    virtual SkShader::Context* createContext(const SkBitmap& device, const SkPaint& paint,
-                                             const SkMatrix& matrix, void* storage) const
+    virtual SkShader::Context* createContext(const ContextRec&, void* storage) const
             SK_OVERRIDE;
     virtual size_t contextSize() const SK_OVERRIDE;
 
     class TransparentShaderContext : public SkShader::Context {
     public:
-        TransparentShaderContext(const SkTransparentShader& shader, const SkBitmap& device,
-                                 const SkPaint& paint, const SkMatrix& matrix);
+        TransparentShaderContext(const SkTransparentShader& shader, const ContextRec&);
         virtual ~TransparentShaderContext();
 
         virtual uint32_t getFlags() const SK_OVERRIDE;