Attempt to call CFNetworkCopyProxiesForURL to mitigate leak.

resolver_mac.c

@@ -156,6 +156,19 @@ bool proxy_resolver_mac_get_proxies_for_url(void *ctx, const char *url) {
         goto mac_done;
     }
 
+    // There is a known issue mentioned in Chromium source, that the run loop instance 
+    // returned by CFNetworkExecuteProxyAutoConfigurationURL leaks. (rdar://problem/5530166)
+
+    // Additionally it is discussed on these forums:
+    //   http://www.openradar.appspot.com/20974299
+    //   https://forums.developer.apple.com/forums/thread/724883
+
+    // The workaround is to first call CFNetworkCopyProxiesForURL to initialize the CFNetwork state.
+
+    CFArrayRef ignore = CFNetworkCopyProxiesForURL(target_url_ref, NULL);
+    if (ignore)
+        CFRelease(ignore);
+
     CFStreamClientContext context = {0, proxy_resolver, NULL, NULL, NULL};
 
     CFRunLoopSourceRef run_loop = CFNetworkExecuteProxyAutoConfigurationURL(
@@ -165,12 +178,6 @@ bool proxy_resolver_mac_get_proxies_for_url(void *ctx, const char *url) {
         LOG_ERROR("Failed to execute pac url (%" PRId64 ")\n", proxy_resolver->error);
         goto mac_done;
     }
-
-    // According to Chromium comments, the run loop instance returned by 
-    // CFNetworkExecuteProxyAutoConfigurationURL leaks.
-    // http://www.openradar.appspot.com/20974299
-    // https://forums.developer.apple.com/forums/thread/724883
-
     CFRunLoopAddSource(CFRunLoopGetCurrent(), run_loop, PROXY_RESOLVER_RUN_LOOP);
     CFRunLoopRunInMode(PROXY_RESOLVER_RUN_LOOP, PROXY_RESOLVER_TIMEOUT_SEC, false);
     CFRunLoopRemoveSource(CFRunLoopGetCurrent(), run_loop, PROXY_RESOLVER_RUN_LOOP);