change asABitmap to isABitmap on shader

src/core/SkPictureCommon.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 // Some shared code used by both SkBigPicture and SkMiniPicture.
 //   SkTextHunter   -- SkRecord visitor that returns true when the op draws text.
 //   SkBitmapHunter -- SkRecord visitor that returns true when the op draws a bitmap.
@@ skipping 41 matching lines @@
     // If not, look for one in its paint (if it has a paint).
     template <typename T>
     static SK_WHEN(!HasMember_bitmap<T>, bool) CheckBitmap(const T& r) { return CheckPaint(r); }
 
     // If we have a paint, dig down into the effects looking for a bitmap.
     template <typename T>
     static SK_WHEN(HasMember_paint<T>, bool) CheckPaint(const T& r) {
         const SkPaint* paint = AsPtr(r.paint);
         if (paint) {
             const SkShader* shader = paint->getShader();
-            if (shader &&
-                shader->asABitmap(nullptr, nullptr, nullptr) == SkShader::kDefault_BitmapType) {
+            if (shader && shader->isABitmap()) {
                 return true;
             }
         }
         return false;
     }
 
     // If we don't have a paint, that non-paint has no bitmap.
     template <typename T>
     static SK_WHEN(!HasMember_paint<T>, bool) CheckPaint(const T&) { return false; }
 };
@@ skipping 53 matching lines @@
     template <typename T>
     SK_WHEN(HasMember_paint<T>, void) operator()(const T& op) {
         this->checkPaint(AsPtr(op.paint));
     }
 
     template <typename T>
     SK_WHEN(!HasMember_paint<T>, void) operator()(const T& op) { /* do nothing */ }
 
     int fNumSlowPathsAndDashEffects;
 };