Factor out DumpRecord method from dump_record tool for later use

gyp/tools.gyp

 # GYP file to build various tools.
 #
 # To build on Linux:
 #  ./gyp_skia tools.gyp && make tools
 #
 {
   'includes': [
     'apptype_console.gypi',
   ],
   'targets': [
@@ skipping 330 matching lines @@
         'flags.gyp:flags',
         'skia_lib.gyp:skia_lib',
         'record.gyp:*',
       ],
     },
     {
       'target_name': 'dump_record',
       'type': 'executable',
       'sources': [
         '../tools/dump_record.cpp',
+        '../tools/DumpRecord.cpp',
         '../tools/LazyDecodeBitmap.cpp',
       ],
       'include_dirs': [
         '../src/core/',
         '../src/images',
         '../src/lazy',
         '../src/record',
       ],
       'dependencies': [
         'bench.gyp:bench_timer',
@@ skipping 251 matching lines @@
             'type': 'executable',
             'sources': [
               '../tools/win_lcid.cpp',
             ],
           },
         ],
       },
     ],
   ],
 }