Wait a second before initializing the Mac notifier thread.

This should prevent slowing down Mac startup.
BUG=34926

Review URL: http://codereview.chromium.org/593039

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@38679 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 32 insertions, 9 deletions

diff --git a/net/base/network_change_notifier_mac.cc b/net/base/network_change_notifier_mac.cc
index f0583db..2dd1b4d 100644
--- a/net/base/network_change_notifier_mac.cc
+++ b/net/base/network_change_notifier_mac.cc
@@ -28,6 +28,7 @@
 #include <SystemConfiguration/SCSchemaDefinitions.h>
 #include <algorithm>
 #include "base/logging.h"
+#include "base/message_loop.h"
 #include "base/scoped_cftyperef.h"
 #include "base/thread.h"
 
@@ -218,15 +219,26 @@ void NetworkChangeNotifierThread::Init() {
 }  // namespace
 
 NetworkChangeNotifierMac::NetworkChangeNotifierMac()
-// http://crbug.com/34926: This might be slowing down Mac startup.  Disable the
-// helper thread to see if that improves mac startup times.
-//    : notifier_thread_(
-//          new NetworkChangeNotifierThread(MessageLoop::current(), this)) {
-//  base::Thread::Options thread_options;
-//  thread_options.message_loop_type = MessageLoop::TYPE_UI;
-//  notifier_thread_->StartWithOptions(thread_options);
-      : notifier_thread_(NULL) {}
+    : notifier_thread_(NULL),
+      method_factory_(this) {
+  // TODO(willchan): Look to see if there's a better signal for when it's ok to
+  // initialize this, rather than just delaying it by a fixed time.
+  const int kNotifierThreadInitializationDelayMS = 1000;
+  MessageLoop* loop = MessageLoop::current();
+  loop->PostDelayedTask(
+      FROM_HERE,
+      method_factory_.NewRunnableMethod(
+          &NetworkChangeNotifierMac::InitializeNotifierThread, loop),
+      kNotifierThreadInitializationDelayMS);
+}
 
 NetworkChangeNotifierMac::~NetworkChangeNotifierMac() {}
 
+void NetworkChangeNotifierMac::InitializeNotifierThread(MessageLoop* loop) {
+  notifier_thread_.reset(new NetworkChangeNotifierThread(loop, this));
+  base::Thread::Options thread_options;
+  thread_options.message_loop_type = MessageLoop::TYPE_UI;
+  notifier_thread_->StartWithOptions(thread_options);
+}
+
 }  // namespace net
diff --git a/net/base/network_change_notifier_mac.h b/net/base/network_change_notifier_mac.h
index cbf0128f..5e777f4 100644
--- a/net/base/network_change_notifier_mac.h
+++ b/net/base/network_change_notifier_mac.h
@@ -8,9 +8,11 @@
 #include "base/basictypes.h"
 #include "base/ref_counted.h"
 #include "base/scoped_ptr.h"
+#include "base/task.h"
 #include "net/base/network_change_notifier.h"
 #include "net/base/network_change_notifier_helper.h"
 
+class MessageLoop;
 namespace base {
 class Thread;
 }  // namespace base
@@ -38,11 +40,20 @@ class NetworkChangeNotifierMac : public NetworkChangeNotifier {
   
   virtual ~NetworkChangeNotifierMac();
 
+  // Initializes the notifier thread.  The SystemConfiguration calls in this
+  // function can lead to contention early on, so we invoke this function later
+  // on in startup to keep it fast.
+  // See http://crbug.com/34926 for details.
+  void InitializeNotifierThread(MessageLoop* loop);
+
   // Receives the OS X network change notifications on this thread.
-  const scoped_ptr<base::Thread> notifier_thread_;
+  scoped_ptr<base::Thread> notifier_thread_;
 
   internal::NetworkChangeNotifierHelper helper_;
 
+  // Used to initialize the notifier thread.
+  ScopedRunnableMethodFactory<NetworkChangeNotifierMac> method_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifierMac);
 };