Fix python scripts in src/tools/

tools/code_coverage/process_coverage.py

-#!/usr/bin/python
+#!/usr/bin/env python
 # 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.
 
 
 """Script to clean the lcov files and convert it to HTML
 
 TODO(niranjan): Add usage information here
 """
 
@@ skipping 326 matching lines @@
     if num_fails < MAX_FAILURES:
       print 'fail, retrying (%d)' % num_fails
       time.sleep(5)
       SendPost(req)
     else:
       print 'POST request exceeded allowed retries.'
       raise
 
 
 def main():
-  if sys.platform[:5] != 'linux': # Run this only on Linux
+  if not sys.platform.startswith('linux'):
     print 'This script is supported only on Linux'
-    os.exit(1)
+    return 0
 
   # Command line parsing
   parser = optparse.OptionParser()
   parser.add_option('-p',
                     '--platform',
                     dest='platform',
                     default=None,
                     help=('Platform that the locv file was generated on. Must'
                           'be one of {win32, linux2, linux3, macosx}'))
   parser.add_option('-s',
@@ skipping 27 matching lines @@
   if options.dash_root == None:
     parser.error('Dashboard root not specified')
   if options.post_url == None:
     parser.error('Post URL not specified')
   if options.platform == 'win32':
     CleanWin32Lcov(options.lcov_path, options.src_dir)
     percent = GenerateHtml(options.lcov_path, options.dash_root)
     if percent == None:
       # TODO(niranjan): Add logging.
       print 'Failed to generate code coverage'
-      os.exit(1)
+      return 1
     else:
       # TODO(niranjan): Do something with the code coverage numbers
       pass
   else:
     print 'Unsupported platform'
-    os.exit(1)
+    return 1
 
   # Prep coverage results for dashboard and post new set.
   parsed_data = ParseCoverageDataForDashboard(options.lcov_path)
   PostResultsToDashboard(options.lcov_path, parsed_data, options.post_url)
+  return 0
 
 
 if __name__ == '__main__':
-  main()
+  sys.exit(main())