Disable flaky NetworkContextConfigurationBrowserTest.ProxyConfig

BUG=823077
TBR=rhalavati@chromium.org,eroman@chromium.org

Change-Id: I1aa9de378251746704f9c358de45f5ff1540397e
Reviewed-on: https://chromium-review.googlesource.com/973607Reviewed-by: Alexander Potapenko <glider@chromium.org>
Commit-Queue: Alexander Potapenko <glider@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544761}

chrome/browser/net/network_context_configuration_browsertest.cc

@@ -575,7 +575,9 @@ IN_PROC_BROWSER_TEST_P(NetworkContextConfigurationBrowserTest, DiskCache) {
   }
 }
 
-IN_PROC_BROWSER_TEST_P(NetworkContextConfigurationBrowserTest, ProxyConfig) {
+// Flaky, see https://crbug.com/823077
+IN_PROC_BROWSER_TEST_P(NetworkContextConfigurationBrowserTest,
+                       DISABLED_ProxyConfig) {
   SetProxyPref(embedded_test_server()->host_port_pair());
   TestProxyConfigured();
 }