Slim down set of things updated by roll script

mojo/tools/roll/update_from_chromium.py

 #!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import argparse
 import json
 import os
 import subprocess
 import sys
 import urllib2
 from utils import commit
 from utils import mojo_root_dir
 from utils import system
 
 import patch
 
-# These directories are snapshotted from chromium without modifications.
-dirs_to_snapshot = [
+# //base and its dependencies
+base_deps = [
     "base",
+    "testing",
+    "third_party/ashmem",
+    "third_party/libevent",
+    "third_party/libxml", # via //base/test
+    "third_party/modp_b64",
+    "third_party/tcmalloc",
+]
+
+# //build and its dependencies
+build_deps = [
     "build",
-    "cc",
-    "gpu",
-    "sandbox/linux",
-    "skia",
-    "testing",
     "third_party/android_testrunner",
-    "third_party/ashmem",
     "third_party/binutils",
-    "third_party/boringssl",
-    "third_party/brotli",
-    "third_party/checkstyle",
-    "third_party/cython",
-    "third_party/fontconfig",
-    "third_party/freetype2",
-    "third_party/harfbuzz-ng",
-    "third_party/iccjpeg",
-    "third_party/jinja2",
-    "third_party/jstemplate",
-    "third_party/khronos",
-    "third_party/libXNVCtrl",
-    "third_party/libevent",
-    "third_party/libjpeg",
-    "third_party/libpng",
-    "third_party/libxml",
-    "third_party/markupsafe",
-    "third_party/mesa",
-    "third_party/modp_b64",
-    "third_party/ots",
-    "third_party/ply",
-    "third_party/protobuf",
     "third_party/pymock",
-    "third_party/qcms",
-    "third_party/re2",
-    "third_party/sfntly",
-    "third_party/smhasher",
-    "third_party/tcmalloc",
-    "third_party/yasm",
-    "third_party/zlib",
     "tools/android",
     "tools/clang",
-    "tools/gdb",
     "tools/generate_library_loader",
-    "tools/git",
     "tools/gritsettings",
-    "tools/idl_parser",
-    "tools/json_comment_eater",
-    "tools/linux",
-    "tools/msan",
-    "tools/protoc_wrapper",
     "tools/relocation_packer",
     "tools/valgrind",
-    "tools/vim",
-    "tools/xdisplaycheck",
-    "url",
-    "ui/gl",
-    ]
+]
 
-files_to_copy = ["sandbox/sandbox_export.h",
-    ".clang-format"]
+# //sandbox/linux and its dependencies
+sandbox_deps = [
+    "sandbox/linux",
+]
+
+# things used from //mojo/public
+mojo_sdk_deps = [
+    "third_party/cython",
+]
+
+# These directories are snapshotted from chromium without modifications.
+dirs_to_snapshot = base_deps + build_deps + sandbox_deps + mojo_sdk_deps
+
+files_to_copy = [ "sandbox/sandbox_export.h" ]
 
 # The contents of these files before the roll will be preserved after the roll,
 # even though they live in directories rolled in from Chromium.
 files_not_to_roll = [ "build/module_args/mojo.gni" ]
 
 dirs = dirs_to_snapshot
 
 def chromium_rev_number(src_commit):
   base_url = "https://cr-rev.appspot.com/_ah/api/crrev/v1/commit/"
   commit_info = json.load(urllib2.urlopen(base_url + src_commit))
@@ skipping 41 matching lines @@
 
   print "Restoring files whose contents don't track Chromium"
   for f in files_not_to_roll:
     system(["git", "checkout", pre_roll_commit, "--", f], cwd=mojo_root_dir)
   if files_not_to_roll:
     commit("Restored pre-roll versions of files that don't get rolled")
   return 0
 
 if __name__ == "__main__":
   sys.exit(main())