move SkChecksum and SkEmptyShader to private

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/SkAAClip.cpp',
@@ skipping 212 matching lines @@
 
         '<(skia_src_path)/pipe/SkGPipeRead.cpp',
         '<(skia_src_path)/pipe/SkGPipeWrite.cpp',
 
         '<(skia_include_path)/core/SkAdvancedTypefaceMetrics.h',
         '<(skia_include_path)/core/SkBBHFactory.h',
         '<(skia_include_path)/core/SkBitmap.h',
         '<(skia_include_path)/core/SkBitmapDevice.h',
         '<(skia_include_path)/core/SkBlitRow.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',
         '<(skia_include_path)/core/SkColorPriv.h',
         '<(skia_include_path)/core/SkColorShader.h',
         '<(skia_include_path)/core/SkComposeShader.h',
         '<(skia_include_path)/core/SkData.h',
         '<(skia_include_path)/core/SkDeque.h',
         '<(skia_include_path)/core/SkDevice.h',
@@ skipping 122 matching lines @@
         '<(skia_src_path)/pathops/SkPathOpsPoint.h',
         '<(skia_src_path)/pathops/SkPathOpsQuad.h',
         '<(skia_src_path)/pathops/SkPathOpsRect.h',
         '<(skia_src_path)/pathops/SkPathOpsTriangle.h',
         '<(skia_src_path)/pathops/SkPathOpsTypes.h',
         '<(skia_src_path)/pathops/SkPathWriter.h',
         '<(skia_src_path)/pathops/SkQuarticRoot.h',
         '<(skia_src_path)/pathops/SkReduceOrder.h',
     ],
 }