Teach dart_package to understand the packages/ subdirectory

DEPS

 # This file is automatically processed to create .DEPS.git which is the file
 # that gclient uses under git.
 #
 # See http://code.google.com/p/chromium/wiki/UsingGit
 #
 # To test manually, run:
 #   python tools/deps2git/deps2git.py -o .DEPS.git -w <gclientdir>
 # where <gcliendir> is the absolute path to the directory containing the
 # .gclient file (the parent of 'src').
 #
@@ skipping 282 matching lines @@
   # Pull the prebuilt network service binaries according to
   # mojo/public/tools/NETWORK_SERVICE_VERSION.
   {
     'name': 'download_network_service',
     'pattern': '',
     'action': [ 'python',
                 'src/mojo/public/tools/download_network_service.py',
                 '--tools-directory', '../../../tools',
     ],
   },
+  # Run "pub get" on any directories with checked-in pubspec.yaml files.
+  {
+    'name': 'run_dart_pub_get',
+    'pattern': '',
+    'action': [ 'python',
+                'src/mojo/public/tools/git/dart_pub_get.py',
+                '--repository-root', '../../../..',
+                '--dart-sdk-directory',
+                '../../../../third_party/dart-sdk/dart-sdk',
+    ],
+  },
   {
     # Ensure that we don't accidentally reference any .pyc files whose
     # corresponding .py files have already been deleted.
     'name': 'remove_stale_pyc_files',
     'pattern': 'src/tools/.*\\.py',
     'action': [
         'python',
         'src/tools/remove_stale_pyc_files.py',
         'src/tools',
     ],
   },
   {
     # This downloads binaries for Native Client's newlib toolchain.
     # Done in lieu of building the toolchain from scratch as it can take
     # anywhere from 30 minutes to 4 hours depending on platform to build.
     'name': 'nacltools',
     'pattern': '.',
     'action': [
         'python', 'src/build/download_nacl_toolchains.py',
         '--packages', 'pnacl_newlib',
         'sync', '--extract',
     ],
   }
 ]