Add GrSet class built on top of RedBlackTree

gyp/bench.gypi

 {
   'include_dirs': [
     '../src/core',
     '../src/effects',
     '../src/utils',
   ],
   'dependencies': [
     'skia_lib.gyp:skia_lib',
   ],
   'sources': [
@@ skipping 20 matching lines @@
     '../bench/DecodeBench.cpp',
     '../bench/DeferredCanvasBench.cpp',
     '../bench/DeferredSurfaceCopyBench.cpp',
     '../bench/DisplacementBench.cpp',
     '../bench/FSRectBench.cpp',
     '../bench/FontCacheBench.cpp',
     '../bench/FontScalerBench.cpp',
     '../bench/GameBench.cpp',
     '../bench/GrMemoryPoolBench.cpp',
     '../bench/GrResourceCacheBench.cpp',
+    '../bench/GrOrderedSetBench.cpp',
     '../bench/GradientBench.cpp',
     '../bench/HairlinePathBench.cpp',
     '../bench/ImageCacheBench.cpp',
     '../bench/ImageDecodeBench.cpp',
     '../bench/InterpBench.cpp',
     '../bench/LightingBench.cpp',
     '../bench/LineBench.cpp',
     '../bench/MagnifierBench.cpp',
     '../bench/MathBench.cpp',
     '../bench/Matrix44Bench.cpp',
@@ skipping 28 matching lines @@
     '../bench/StrokeBench.cpp',
     '../bench/TableBench.cpp',
     '../bench/TextBench.cpp',
     '../bench/TileBench.cpp',
     '../bench/VertBench.cpp',
     '../bench/WritePixelsBench.cpp',
     '../bench/WriterBench.cpp',
     '../bench/XfermodeBench.cpp',
   ],
 }