Check Firewall state only initializing mDns from PrintPreview.

chrome/browser/local_discovery/service_discovery_shared_client.cc

 // Copyright 2013 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.
 
 #include "chrome/browser/local_discovery/service_discovery_shared_client.h"
 
 #include "content/public/browser/browser_thread.h"
 
 #if defined(OS_WIN)
 #include "base/files/file_path.h"
@@ skipping 11 matching lines @@
 #if defined(ENABLE_MDNS)
 #include "chrome/browser/local_discovery/service_discovery_client_mdns.h"
 #include "chrome/browser/local_discovery/service_discovery_client_utility.h"
 #endif  // ENABLE_MDNS
 
 namespace {
 
 #if defined(OS_WIN)
 
 bool g_is_firewall_ready = false;
+bool g_is_firewall_state_reported = false;
 
 void ReportFirewallStats() {
+  if (g_is_firewall_state_reported)
+    return;
+  g_is_firewall_state_reported = true;
   base::FilePath exe_path;
   if (!PathService::Get(base::FILE_EXE, &exe_path))
     return;
   base::ElapsedTimer timer;
   scoped_ptr<installer::FirewallManager> manager =
       installer::FirewallManager::Create(BrowserDistribution::GetDistribution(),
                                          exe_path);
   if (!manager)
     return;
   g_is_firewall_ready = manager->CanUseLocalPorts();
@@ skipping 29 matching lines @@
     ServiceDiscoverySharedClient::GetInstance() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   if (g_service_discovery_client)
     return g_service_discovery_client;
 
 #if defined(OS_MACOSX)
   return ServiceDiscoveryClientMacFactory::CreateInstance();
 #else  // OS_MACOSX
 
-#if defined(OS_WIN)
-  static bool reported =
-      BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
-                              base::Bind(&ReportFirewallStats));
+  return new ServiceDiscoveryClientMdns();

[Noam Samuel, 2014/08/27 17:58:56]

Maybe do

if (g_is_firewall_state_reported) {
 return g_is_firewall_ready ? new ServiceDiscoveryClientMdns() : new
ServiceDiscoveryClientUtility();
} else {
 return new ServiceDiscoveryClientUtility();
}

here so users don't get two different ServiceDiscoveryClients? Also if we do
this and then migrate notifications, GetInstance() will almost always do the
right thing.

[Vitaly Buka (NO REVIEWS), 2014/08/27 18:08:27]

Goal is always use ServiceDiscoveryClientMdns. Only preview is exceptional.

On 2014/08/27 17:58:56, Noam Samuel wrote:

+#endif  // OS_MACOSX
+}
+
+// static
+void ServiceDiscoverySharedClient::GetInstanceWithoutAlert(
+    const GetInstanceCallback& callback) {
+#if !defined(OS_WIN)
+
+  scoped_refptr<ServiceDiscoverySharedClient> result = GetInstance();
+  return callback.Run(result);
+
+#else   // OS_WIN
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   // TODO(vitalybuka): Switch to |ServiceDiscoveryClientMdns| after we find what
   // to do with firewall for user-level installs. crbug.com/366408
-  if (!g_is_firewall_ready)
-    return new ServiceDiscoveryClientUtility();
+  scoped_refptr<ServiceDiscoverySharedClient> result =
+      g_service_discovery_client;
+  if (result)
+    return callback.Run(result);
+
+  if (!g_is_firewall_state_reported) {
+    BrowserThread::PostTaskAndReply(
+        BrowserThread::FILE,
+        FROM_HERE,
+        base::Bind(&ReportFirewallStats),
+        base::Bind(&ServiceDiscoverySharedClient::GetInstanceWithoutAlert,
+                   callback));
+    return;
+  }
+
+  result =
+      g_is_firewall_ready ? GetInstance() : new ServiceDiscoveryClientUtility();
+  callback.Run(result);
 #endif  // OS_WIN
-
-  return new ServiceDiscoveryClientMdns();
-#endif // OS_MACOSX
 }
 
 #else
 
 scoped_refptr<ServiceDiscoverySharedClient>
     ServiceDiscoverySharedClient::GetInstance() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   NOTIMPLEMENTED();
   return NULL;
 }
 
 #endif  // ENABLE_MDNS
 
 }  // namespace local_discovery