Add presubmit checks for TSan suppressions

tools/valgrind/tsan/PRESUBMIT.py

 # Copyright (c) 2011 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 os
+import re
+import sys
+
 """
 See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
 for more details on the presubmit API built into gcl.
 """
 
+def CheckChange(input_api, output_api):
+  """Checks the TSan suppressions files for bad suppressions."""
+
+  # TODO(timurrrr): find out how to do relative imports
+  # and remove this ugly hack. Also, the CheckChange function won't be needed.
+  tools_vg_path = os.path.join(input_api.PresubmitLocalPath(), '..')
+  sys.path.append(tools_vg_path)
+  import suppressions
+
+  return suppressions.PresubmitCheck(input_api, output_api)
+
+def CheckChangeOnUpload(input_api, output_api):
+  return CheckChange(input_api, output_api)
+
+def CheckChangeOnCommit(input_api, output_api):
+  return CheckChange(input_api, output_api)
+
 def GetPreferredTrySlaves():
   return ['linux_tsan']