Force linking with image decoders for images project.

gyp/images.gyp

 {
   'targets': [
     {
       'target_name': 'images',
       'product_name': 'skia_images',
       'type': 'static_library',
       'standalone_static_library': 1,
       'dependencies': [
         'libjpeg.gyp:*',
         'libwebp.gyp:libwebp',
@@ skipping 22 matching lines @@
         '../include/images/SkPageFlipper.h',
 
         '../src/images/bmpdecoderhelper.cpp',
         '../src/images/bmpdecoderhelper.h',
 
         '../src/images/SkBitmapRegionDecoder.cpp',
 
         '../src/images/SkImageDecoder.cpp',
         '../src/images/SkImageDecoder_FactoryDefault.cpp',
         '../src/images/SkImageDecoder_FactoryRegistrar.cpp',
+        # If decoders are added/removed to/from (all/individual)
+        # platform(s), be sure to update SkImageDecoder.cpp:force_linking
+        # so the right decoders will be forced to link.
         '../src/images/SkImageDecoder_libbmp.cpp',
         '../src/images/SkImageDecoder_libgif.cpp',
         '../src/images/SkImageDecoder_libico.cpp',
         '../src/images/SkImageDecoder_libjpeg.cpp',
         '../src/images/SkImageDecoder_libpng.cpp',
         '../src/images/SkImageDecoder_libwebp.cpp',
         '../src/images/SkImageDecoder_wbmp.cpp',
         '../src/images/SkImageEncoder.cpp',
         '../src/images/SkImageEncoder_Factory.cpp',
         '../src/images/SkImageEncoder_argb.cpp',
@@ skipping 106 matching lines @@
       },
     },
   ],
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: