promote SkImage::AlphaType to SkAlphaType

gyp/core.gypi

 # Include this gypi to include all 'core' files
 # The parent gyp/gypi file must define
 #       'skia_src_path'     e.g. skia/trunk/src
 #       'skia_include_path' e.g. skia/trunk/include
 #
 # The skia build defines these in common_variables.gypi
 #
 {
     'sources': [
         '<(skia_src_path)/core/ARGB32_Clamp_Bilinear_BitmapShader.h',
@@ skipping 196 matching lines @@
         '<(skia_src_path)/image/SkSurface.cpp',
 #        '<(skia_src_path)/image/SkSurface_Gpu.cpp',
         '<(skia_src_path)/image/SkSurface_Picture.cpp',
         '<(skia_src_path)/image/SkSurface_Raster.cpp',
 
         '<(skia_src_path)/pipe/SkGPipeRead.cpp',
         '<(skia_src_path)/pipe/SkGPipeWrite.cpp',
 
         '<(skia_include_path)/core/Sk64.h',
         '<(skia_include_path)/core/SkAdvancedTypefaceMetrics.h',
+        '<(skia_include_path)/core/SkAlpha.h',
         '<(skia_include_path)/core/SkBitmap.h',
         '<(skia_include_path)/core/SkBitmapDevice.h',
         '<(skia_include_path)/core/SkBlitRow.h',
         '<(skia_include_path)/core/SkBounder.h',
         '<(skia_include_path)/core/SkCanvas.h',
         '<(skia_include_path)/core/SkChecksum.h',
         '<(skia_include_path)/core/SkChunkAlloc.h',
         '<(skia_include_path)/core/SkClipStack.h',
         '<(skia_include_path)/core/SkColor.h',
         '<(skia_include_path)/core/SkColorFilter.h',
@@ skipping 144 matching lines @@
         '<(skia_src_path)/pathops/SkQuarticRoot.h',
         '<(skia_src_path)/pathops/SkReduceOrder.h',
     ],
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: