Move SkComposeImageFilter into its own {.h, .cpp} files

gyp/effects.gypi

 # Include this gypi to include all 'effects' 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)/effects/Sk1DPathEffect.cpp',
     '<(skia_src_path)/effects/Sk2DPathEffect.cpp',
     '<(skia_src_path)/effects/SkArithmeticMode.cpp',
     '<(skia_src_path)/effects/SkAvoidXfermode.cpp',
     '<(skia_src_path)/effects/SkBicubicImageFilter.cpp',
     '<(skia_src_path)/effects/SkBitmapSource.cpp',
     '<(skia_src_path)/effects/SkBlurDrawLooper.cpp',
     '<(skia_src_path)/effects/SkBlurMask.cpp',
     '<(skia_src_path)/effects/SkBlurMask.h',
     '<(skia_src_path)/effects/SkBlurImageFilter.cpp',
     '<(skia_src_path)/effects/SkBlurMaskFilter.cpp',
     '<(skia_src_path)/effects/SkColorFilters.cpp',
     '<(skia_src_path)/effects/SkColorFilterImageFilter.cpp',
     '<(skia_src_path)/effects/SkColorMatrix.cpp',
     '<(skia_src_path)/effects/SkColorMatrixFilter.cpp',
+    '<(skia_src_path)/effects/SkComposeImageFilter.cpp',
     '<(skia_src_path)/effects/SkCornerPathEffect.cpp',
     '<(skia_src_path)/effects/SkDashPathEffect.cpp',
     '<(skia_src_path)/effects/SkDiscretePathEffect.cpp',
     '<(skia_src_path)/effects/SkDisplacementMapEffect.cpp',
     '<(skia_src_path)/effects/SkEmbossMask.cpp',
     '<(skia_src_path)/effects/SkEmbossMask.h',
     '<(skia_src_path)/effects/SkEmbossMask_Table.h',
     '<(skia_src_path)/effects/SkEmbossMaskFilter.cpp',
     '<(skia_src_path)/effects/SkGpuBlurUtils.h',
     '<(skia_src_path)/effects/SkGpuBlurUtils.cpp',
@@ skipping 74 matching lines @@
     '<(skia_include_path)/effects/SkTransparentShader.h',
     '<(skia_include_path)/effects/SkMagnifierImageFilter.h',
   ],
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: