Update to Chromium version 71.0.3578.0 (#599034)

patch/patch.cfg

@@ -232,6 +232,13 @@ patches = [
     # Allow CEF to intercept GetBrowserContext*InIncognito functions.
     'name': 'chrome_browser_profiles',
   },
+  {
+    # Support direct access to NetExportFileWriter via BrowserProcess instead
+    # of adding a dependency on SystemNetworkContextManager (see
+    # https://crrev.com/6ed14d99e9).
+    # TODO(cef): Consider removing this once we support NetworkService.
+    'name': 'chrome_browser_net_export',
+  },
   {
     # Allow CEF to share Chrome plugin loading code.
     'name': 'chrome_plugins',