[mb] Copy MB from Chromium repo

DEPS

 # Note: The buildbots evaluate this file with CWD set to the parent
 # directory and assume that the root of the checkout is in ./v8/, so
 # all paths in here must match this assumption.
 
 vars = {
   "git_url": "https://chromium.googlesource.com",
 }
 
 deps = {
   "v8/build":
     Var("git_url") + "/chromium/src/build.git" + "@" + "87f8ed60519428c429030cd9ccb3feaf9f616881",
   "v8/tools/gyp":
     Var("git_url") + "/external/gyp.git" + "@" + "702ac58e477214c635d9b541932e75a95d349352",
   "v8/third_party/icu":
     Var("git_url") + "/chromium/deps/icu.git" + "@" + "2341038bf72869a5683a893a2b319a48ffec7f62",
   "v8/third_party/instrumented_libraries":
     Var("git_url") + "/chromium/src/third_party/instrumented_libraries.git" + "@" + "f15768d7fdf68c0748d20738184120c8ab2e6db7",
   "v8/buildtools":
     Var("git_url") + "/chromium/buildtools.git" + "@" + "adb8bf4e8fc92aa1717bf151b862d58e6f27c4f2",
   "v8/base/trace_event/common":
     Var("git_url") + "/chromium/src/base/trace_event/common.git" + "@" + "315bf1e2d45be7d53346c31cfcc37424a32c30c8",
   "v8/third_party/WebKit/Source/platform/inspector_protocol":
     Var("git_url") + "/chromium/src/third_party/WebKit/Source/platform/inspector_protocol.git" + "@" + "a78b8834da38e5bca9eb5f0d8c28ffe4561dd224",
   "v8/third_party/jinja2":
     Var("git_url") + "/chromium/src/third_party/jinja2.git" + "@" + "2222b31554f03e62600cd7e383376a7c187967a1",
   "v8/third_party/markupsafe":
     Var("git_url") + "/chromium/src/third_party/markupsafe.git" + "@" + "484a5661041cac13bfc688a26ec5434b05d18961",
-  "v8/tools/mb":
-    Var('git_url') + '/chromium/src/tools/mb.git' + '@' + "2f9349ee2aec6dd7b167b26cbbcac2891a9649ab",
   "v8/tools/swarming_client":
     Var('git_url') + '/external/swarming.client.git' + '@' + "e4288c3040a32f2e7ad92f957668f2ee3d36e5a6",
   "v8/testing/gtest":
     Var("git_url") + "/external/github.com/google/googletest.git" + "@" + "6f8a66431cb592dad629028a50b3dd418a408c87",
   "v8/testing/gmock":
     Var("git_url") + "/external/googlemock.git" + "@" + "0421b6f358139f02e102c9c332ce19a33faf75be",
   "v8/test/benchmarks/data":
     Var("git_url") + "/v8/deps/third_party/benchmarks.git" + "@" + "05d7188267b4560491ff9155c5ee13e207ecd65f",
   "v8/test/mozilla/data":
     Var("git_url") + "/v8/deps/third_party/mozilla-tests.git" + "@" + "f6c578a10ea707b1a8ab0b88943fe5115ce2b9be",
@@ skipping 237 matching lines @@
     'name': 'clang',
     'pattern': '.',
     'action': ['python', 'v8/tools/clang/scripts/update.py', '--if-needed'],
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "pattern": ".",
     "action": ["python", "v8/gypfiles/gyp_v8"],
   },
 ]