make SkColorShader private, use public factory

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)/c/sk_surface.cpp',
@@ skipping 35 matching lines @@
         '<(skia_src_path)/core/SkBlitter_Sprite.cpp',
         '<(skia_src_path)/core/SkBuffer.cpp',
         '<(skia_src_path)/core/SkCachedData.cpp',
         '<(skia_src_path)/core/SkCanvas.cpp',
         '<(skia_src_path)/core/SkCanvasDrawable.cpp',
         '<(skia_src_path)/core/SkCanvasDrawable.h',
         '<(skia_src_path)/core/SkChunkAlloc.cpp',
         '<(skia_src_path)/core/SkClipStack.cpp',
         '<(skia_src_path)/core/SkColor.cpp',
         '<(skia_src_path)/core/SkColorFilter.cpp',
+        '<(skia_src_path)/core/SkColorShader.h',
         '<(skia_src_path)/core/SkColorTable.cpp',
         '<(skia_src_path)/core/SkComposeShader.cpp',
         '<(skia_src_path)/core/SkConfig8888.cpp',
         '<(skia_src_path)/core/SkConfig8888.h',
         '<(skia_src_path)/core/SkConvolver.cpp',
         '<(skia_src_path)/core/SkConvolver.h',
         '<(skia_src_path)/core/SkCoreBlitters.h',
         '<(skia_src_path)/core/SkCubicClipper.cpp',
         '<(skia_src_path)/core/SkCubicClipper.h',
         '<(skia_src_path)/core/SkData.cpp',
@@ skipping 170 matching lines @@
         '<(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/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',
         '<(skia_include_path)/core/SkDither.h',
         '<(skia_include_path)/core/SkDraw.h',
         '<(skia_include_path)/core/SkDrawFilter.h',
         '<(skia_include_path)/core/SkDrawLooper.h',
         '<(skia_include_path)/core/SkEndian.h',
         '<(skia_include_path)/core/SkError.h',
@@ skipping 117 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',
     ],
 }