Reland of PyLint fixes for tools-webrtc and webrtc/tools (patchset #1 id:1 of https://codereview.webrtc.org/2737233003/ )

Reason for revert:
Fixing errors for reland. I have tested that this does not make Chromium video quality tests fail.

Original issue's description:
> Revert of PyLint fixes for tools-webrtc and webrtc/tools (patchset #3 id:40001 of https://codereview.webrtc.org/2736233003/ )
>
> Reason for revert:
> Fails video quality tests in Chrome:  http://build.chromium.org/p/chromium.webrtc.fyi/builders/Win10%20Tester/builds/6568
> I should have looked more closer at those :(
>
> Original issue's description:
> > PyLint fixes for tools-webrtc and webrtc/tools
> >
> > Fix a lot of errors before bringing in the new config in
> > https://codereview.webrtc.org/2737963003/
> >
> > BUG=webrtc:7303
> > NOTRY=True
> >
> > Review-Url: https://codereview.webrtc.org/2736233003
> > Cr-Commit-Position: refs/heads/master@{#17137}
> > Committed: https://chromium.googlesource.com/external/webrtc/+/f5318e1f391859c82aaa47b297429e50f41f6b3c
>
> TBR=oprypin@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=webrtc:7303
>
> Review-Url: https://codereview.webrtc.org/2737233003
> Cr-Commit-Position: refs/heads/master@{#17142}
> Committed: https://chromium.googlesource.com/external/webrtc/+/94f4d9effc3fa1ee6a6a48a7bbdef6684defd1dc

NOTRY=true
BUG=webrtc:7312

Review-Url: https://codereview.webrtc.org/2741733003
Cr-Commit-Position: refs/heads/master@{#17541}
diff --git a/tools-webrtc/network_emulator/emulate.py b/tools-webrtc/network_emulator/emulate.py
index 82a6f48..08049a5 100755
--- a/tools-webrtc/network_emulator/emulate.py
+++ b/tools-webrtc/network_emulator/emulate.py
@@ -55,14 +55,14 @@
     return self.epilog
 
 
-def _get_external_ip():
+def _GetExternalIp():
   """Finds out the machine's external IP by connecting to google.com."""
   external_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
   external_socket.connect(('google.com', 80))
   return external_socket.getsockname()[0]
 
 
-def _parse_args():
+def _ParseArgs():
   """Define and parse the command-line arguments."""
   presets_string = '\n'.join(str(p) for p in _PRESETS)
   parser = NonStrippingEpilogOptionParser(epilog=(
@@ -123,11 +123,11 @@
   except ValueError:
     parser.error('Invalid port range specified.')
 
-  _set_logger(options.verbose)
+  _InitLogging(options.verbose)
   return options
 
 
-def _set_logger(verbose):
+def _InitLogging(verbose):
   """Setup logging."""
   log_level = _DEFAULT_LOG_LEVEL
   if verbose:
@@ -135,8 +135,8 @@
   logging.basicConfig(level=log_level, format='%(message)s')
 
 
-def _main():
-  options = _parse_args()
+def main():
+  options = _ParseArgs()
 
   # Build a configuration object. Override any preset configuration settings if
   # a value of a setting was also given as a flag.
@@ -154,19 +154,19 @@
   emulator = network_emulator.NetworkEmulator(connection_config,
                                               options.port_range)
   try:
-    emulator.check_permissions()
+    emulator.CheckPermissions()
   except network_emulator.NetworkEmulatorError as e:
     logging.error('Error: %s\n\nCause: %s', e.fail_msg, e.error)
     return -1
 
   if not options.target_ip:
-    external_ip = _get_external_ip()
+    external_ip = _GetExternalIp()
   else:
     external_ip = options.target_ip
 
   logging.info('Constraining traffic to/from IP: %s', external_ip)
   try:
-    emulator.emulate(external_ip)
+    emulator.Emulate(external_ip)
     logging.info('Started network emulation with the following configuration:\n'
                  '  Receive bandwidth: %s kbps (%s kB/s)\n'
                  '  Send bandwidth   : %s kbps (%s kB/s)\n'
@@ -184,7 +184,7 @@
                  options.port_range[0], options.port_range[1])
     raw_input('Press Enter to abort Network Emulation...')
     logging.info('Flushing all Dummynet rules...')
-    network_emulator.cleanup()
+    network_emulator.Cleanup()
     logging.info('Completed Network Emulation.')
     return 0
   except network_emulator.NetworkEmulatorError as e:
@@ -192,4 +192,4 @@
     return -2
 
 if __name__ == '__main__':
-  sys.exit(_main())
+  sys.exit(main())