Add tools/flatten to flatten nested pictures in .skps.

gyp/tools.gyp

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
     # GYP file to build various tools.
 #
 # To build on Linux:
 #  ./gyp_skia tools.gyp && make tools
 #
 {
   'includes': [
     'apptype_console.gypi',
   ],
   'targets': [
     {
       # Build all executable targets defined below.
       'target_name': 'tools',
       'type': 'none',
       'dependencies': [
         'bench_pictures',
         'chrome_fuzz',
         'dump_record',
         'filter',
+        'flatten',
         'gpuveto',
         'lua_app',
         'lua_pictures',
         'imgconv',
         'pinspect',
         'render_pdfs',
         'render_pictures',
         'skdiff',
         'skhello',
         'skp2svg',
@@ skipping 236 matching lines @@
       ],
       'include_dirs': [
         '../src/core/',
       ],
       'dependencies': [
         'flags.gyp:flags',
         'skia_lib.gyp:skia_lib',
       ],
     },
     {
+      'target_name': 'flatten',
+      'type': 'executable',
+      'sources': [
+        '../tools/flatten.cpp',
+      ],
+      'dependencies': [
+        'skia_lib.gyp:skia_lib',
+      ],
+    },
+    {
       # Superseded by dm, should be removed.
       'target_name': 'skp2svg',
       'type': 'executable',
       'sources': [
         '../src/svg/skp2svg.cpp',
         '../tools/LazyDecodeBitmap.cpp',
       ],
       'include_dirs': [
         '../src/core/',
         '../src/lazy/',
@@ skipping 482 matching lines @@
               'flags.gyp:flags',
               'skia_lib.gyp:skia_lib',
               'resources',
             ],
           },
         ],
       },
     ],
   ],
 }