Remove unused (by clients) SkUnitMapper (https://codereview.chromium.org/283273002/)

gyp/utils.gyp

 # Gyp for utils.
 {
   'targets': [
     {
       'target_name': 'utils',
       'product_name': 'skia_utils',
       'type': 'static_library',
       'standalone_static_library': 1,
       'dependencies': [
         'core.gyp:*',
@@ skipping 38 matching lines @@
         '../include/utils/SkNoSaveLayerCanvas.h',
         '../include/utils/SkNWayCanvas.h',
         '../include/utils/SkNullCanvas.h',
         '../include/utils/SkParse.h',
         '../include/utils/SkParsePaint.h',
         '../include/utils/SkParsePath.h',
         '../include/utils/SkPictureUtils.h',
         '../include/utils/SkRandom.h',
         '../include/utils/SkRTConf.h',
         '../include/utils/SkProxyCanvas.h',
-        '../include/utils/SkUnitMappers.h',
         '../include/utils/SkWGL.h',
 
         '../src/utils/SkBase64.cpp',
         '../src/utils/SkBase64.h',
         '../src/utils/SkBitmapHasher.cpp',
         '../src/utils/SkBitmapHasher.h',
         '../src/utils/SkBitSet.cpp',
         '../src/utils/SkBitSet.h',
         '../src/utils/SkBoundaryPatch.cpp',
         '../src/utils/SkFrontBufferedStream.cpp',
@@ skipping 33 matching lines @@
         '../src/utils/SkThreadUtils.h',
         '../src/utils/SkThreadUtils_pthread.cpp',
         '../src/utils/SkThreadUtils_pthread.h',
         '../src/utils/SkThreadUtils_pthread_linux.cpp',
         '../src/utils/SkThreadUtils_pthread_mach.cpp',
         '../src/utils/SkThreadUtils_pthread_other.cpp',
         '../src/utils/SkThreadUtils_win.cpp',
         '../src/utils/SkThreadUtils_win.h',
         '../src/utils/SkTFitsIn.h',
         '../src/utils/SkTLogic.h',
-        '../src/utils/SkUnitMappers.cpp',
 
         #mac
         '../include/utils/mac/SkCGUtils.h',
         '../src/utils/mac/SkCreateCGImageRef.cpp',
 
         #windows
         '../include/utils/win/SkAutoCoInitialize.h',
         '../include/utils/win/SkHRESULT.h',
         '../include/utils/win/SkIStream.h',
         '../include/utils/win/SkTScopedComPtr.h',
@@ skipping 107 matching lines @@
       ],
       'direct_dependent_settings': {
         'include_dirs': [
           '../include/utils',
           '../src/utils',
         ],
       },
     },
   ],
 }