Fixes two connection issues with memory_infra_remote_dump.

tracing/bin/memory_infra_remote_dump

 #!/usr/bin/env python
 # Copyright 2017 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.
 """Grabs before/after memory dumps using the devtools remote protocol.
 
 To use it you first start Chrome with remote debugging enabled then run the
 script which will take a memory dump, wait for you to press enter, take 
 another memory dump and finally save a trace file. For example:
 
@@ skipping 16 matching lines @@
 $ ./third_party/catapult/tracing/bin/memory_infra_remote_dump --port=1234
 ...
 [Press enter to stop tracing]
 ...
 /var/folders/18/gl6q632j20nc_tw5g9l03dhc007g45/T/trace_20s191.json: 835 KB
 """
 
 import argparse
 import json
 import os
+import requests
 import sys
 import tempfile
 import time
 
 try:
   import websocket
 except ImportError:
   print 'Please run: pip install --user websocket-client'
   sys.exit(1)
 
 
 class TracingDevtoolsClient(object):
   def __init__(self, host, port):
-    url = 'ws://%s:%s/devtools/browser' % (host, port)
+    r = requests.get('http://%s:%s/json/version' % (host, port))
+    url = r.json()['webSocketDebuggerUrl']
     print 'Connecting to ' + url
-    self.ws = websocket.CreateConnection(url)
+    self.ws = websocket.create_connection(url)
     self.cmd = 0
 
   def send(self, method, params={}):
     self.cmd += 1
     self.ws.send(
         json.dumps({'id': self.cmd, 'method': method, 'params': params}))
     resp = self.recv()
     assert resp['id'] == self.cmd
     return resp.get('result', {})
 
@@ skipping 57 matching lines @@
 
   if args.output_trace is None:
     trace_fd = tempfile.NamedTemporaryFile(prefix='trace_', suffix='.json',
                                            delete=False)
   else:
     trace_fd = open(args.output_trace, 'wb')
 
   cli = TracingDevtoolsClient(args.host, args.port)
   cli.dump(trace_fd)
   print '\n%s: %d KB' % (trace_fd.name, os.stat(trace_fd.name).st_size / 1000)