Add alpha type to texture producer

src/gpu/GrImageIDTextureAdjuster.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.
  */
 
 #ifndef GrImageIDTextureAdjuster_DEFINED
 #define GrImageIDTextureAdjuster_DEFINED
 
@@ skipping 11 matching lines @@
 public:
     GrBitmapTextureMaker(GrContext* context, const SkBitmap& bitmap);
 
 protected:
     GrTexture* refOriginalTexture(bool willBeMipped, SkSourceGammaTreatment) override;
 
     void makeCopyKey(const CopyParams& copyParams, GrUniqueKey* copyKey) override;
 
     void didCacheCopy(const GrUniqueKey& copyKey) override;
 
+    SkAlphaType alphaType() const override;
     SkColorSpace* getColorSpace() override;
 
 private:
     const SkBitmap  fBitmap;
     GrUniqueKey     fOriginalKey;
 
     typedef GrTextureMaker INHERITED;
 };
 
 /** This class manages the conversion of generator-backed images to GrTextures. If the caching hint
     is kAllow the image's ID is used for the cache key. */
 class GrImageTextureMaker : public GrTextureMaker {
 public:
     GrImageTextureMaker(GrContext* context, SkImageCacherator* cacher, const SkImage* client,
                         SkImage::CachingHint chint);
 
 protected:
     // TODO: consider overriding this, for the case where the underlying generator might be
     //       able to efficiently produce a "stretched" texture natively (e.g. picture-backed)
     //          GrTexture* generateTextureForParams(const CopyParams&) override;
 
     GrTexture* refOriginalTexture(bool willBeMipped, SkSourceGammaTreatment) override;
     void makeCopyKey(const CopyParams& stretch, GrUniqueKey* paramsCopyKey) override;
     void didCacheCopy(const GrUniqueKey& copyKey) override;
 
+    SkAlphaType alphaType() const override;
     SkColorSpace* getColorSpace() override;
 
 private:
     SkImageCacherator*      fCacher;
     const SkImage*          fClient;
     GrUniqueKey             fOriginalKey;
     SkImage::CachingHint    fCachingHint;
 
     typedef GrTextureMaker INHERITED;
 };
 
 #endif