Moving gn_isolate_map.pyl to tools-webrtc/mb

BUG=webrtc:7030
R=kjellander@webrtc.org

Review-Url: https://codereview.webrtc.org/2648353004 .
Cr-Commit-Position: refs/heads/master@{#16262}

tools-webrtc/mb/mb.py

@@ -48,8 +48,7 @@ class MetaBuildWrapper(object):
   def __init__(self):
     self.chromium_src_dir = CHROMIUM_SRC_DIR
     self.default_config = os.path.join(SCRIPT_DIR, 'mb_config.pyl')
-    self.default_isolate_map = os.path.join(self.chromium_src_dir, 'testing',
-                                            'buildbot', 'gn_isolate_map.pyl')
+    self.default_isolate_map = os.path.join(SCRIPT_DIR, 'gn_isolate_map.pyl')
     self.executable = sys.executable
     self.platform = sys.platform
     self.sep = os.sep