Allow the consumer of storage monitor to register callback when the initialization is completed.

chrome/browser/storage_monitor/storage_monitor.cc

Index: chrome/browser/storage_monitor/storage_monitor.cc
diff --git a/chrome/browser/storage_monitor/storage_monitor.cc b/chrome/browser/storage_monitor/storage_monitor.cc
index 682264223c40b147f4446a65e51ef9b9b042da53..11f59f72bca6e06c1f82b57853d9a88c37454e3b 100644
--- a/chrome/browser/storage_monitor/storage_monitor.cc
+++ b/chrome/browser/storage_monitor/storage_monitor.cc
@@ -62,6 +62,11 @@ std::vector<StorageInfo> StorageMonitor::GetAttachedStorage() const {
 }
 
 void StorageMonitor::Initialize(base::Closure callback) {

[Hongbo Min, 2013/05/29 06:53:00]

What is the Initialize used for?

If the StorageMonitor is changing to be created only when needed, could we use
RegisterInitCompletionCallback to register the callbacks wanted and then call
Init to query storage metadata? 

[Greg Billock, 2013/05/29 17:46:34]

If your code needs an initialized storage monitor, you should just call
Initialize() yourself.

Meaning, when the monitor is lazily initialized, you must initialize it before
it'll start working. I think Steve suggested "EnsureInitialized" might be a
better name, which is probably true.

+  RegisterInitCompletedCallback(callback);
+  Init();
+}
+
+void StorageMonitor::RegisterInitCompletedCallback(base::Closure callback) {
   if (initialized_) {
     if (!callback.is_null())
       callback.Run();
@@ -71,8 +76,6 @@ void StorageMonitor::Initialize(base::Closure callback) {
   if (!callback.is_null()) {
     on_initialize_callbacks_.push_back(callback);
   }
-
-  Init();
 }
 
 bool StorageMonitor::IsInitialized() {