Infrastructure changes to support pull saveLayers forward task

src/core/SkPaintPriv.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPaintPriv_DEFINED
 #define SkPaintPriv_DEFINED
 
 class SkBitmap;
 class SkPaint;
 
 #include "SkTypes.h"
 /** Returns true if draw calls that use the paint will completely occlude
     canvas contents that are covered by the draw.
     @param paint The paint to be analyzed, NULL is equivalent to
         the default paint.
     @param bmpReplacesShader a bitmap to be used in place of the paint's
         shader.
     @return true if paint is opaque
 */
 bool isPaintOpaque(const SkPaint* paint,
                    const SkBitmap* bmpReplacesShader = NULL);
+
+/** Returns true if the provided paint has fields which are not
+    immutable (and will thus require deep copying).
+    @param paint the paint to be analyzed
+    @return true if the paint requires a deep copy
+*/
+bool NeedsDeepCopy(const SkPaint& paint);
 #endif