Add a release procedure to SkMallocPixelRef; remove SkDataPixelRef

gyp/tests.gyp

 # GYP file to build unit tests.
 {
   'includes': [
     'apptype_console.gypi',
   ],
   'targets': [
     {
       'target_name': 'tests',
       'type': 'executable',
       'include_dirs' : [
@@ skipping 78 matching lines @@
         '../tests/GrUnitTests.cpp',
         '../tests/HashCacheTest.cpp',
         '../tests/ImageCacheTest.cpp',
         '../tests/ImageDecodingTest.cpp',
         '../tests/ImageFilterTest.cpp',
         '../tests/InfRectTest.cpp',
         '../tests/JpegTest.cpp',
         '../tests/LListTest.cpp',
         '../tests/LayerDrawLooperTest.cpp',
         '../tests/MD5Test.cpp',
+        '../tests/MallocPixelRefTest.cpp',
         '../tests/MathTest.cpp',
         '../tests/MatrixTest.cpp',
         '../tests/Matrix44Test.cpp',
         '../tests/MemoryTest.cpp',
         '../tests/MemsetTest.cpp',
         '../tests/MessageBusTest.cpp',
         '../tests/MetaDataTest.cpp',
         '../tests/MipMapTest.cpp',
         '../tests/OnceTest.cpp',
         '../tests/OSPathTest.cpp',
@@ skipping 68 matching lines @@
       'conditions': [
         [ 'skia_gpu == 1', {
           'include_dirs': [
             '../src/gpu',
           ],
         }],
       ],
     },
   ],
 }