WebView Tools: support Windows for record_netlog.py

record_netlog.py was constructing an on-device path with "os.path." This
isn't correct on Windows, where we want to use posixpath for on-device
paths and os.path for on-host paths.

Fixed: 1156518
Test: validity check the script still works as intended on Linux
Change-Id: I8120bf5416fc957d4cc0605a49d2a32d190aa2e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2577634
Auto-Submit: Nate Fischer <ntfschr@chromium.org>
Commit-Queue: Richard Coles <torne@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845284}

android_webview/tools/record_netlog.py

@@ -14,6 +14,7 @@ from __future__ import print_function
 import argparse
 import logging
 import os
+import posixpath
 import re
 import sys
 import time
@@ -90,7 +91,7 @@ https://chromium.googlesource.com/chromium/src/+/HEAD/android_webview/docs/net-d
 
   package_name = args.package
   device_netlog_file_name = 'netlog.json'
-  device_netlog_path = os.path.join(
+  device_netlog_path = posixpath.join(
       device.GetApplicationDataDirectory(package_name), 'app_webview',
       device_netlog_file_name)