Lazy initialization for PushMessagingEventRouter

chrome/browser/extensions/api/push_messaging/push_messaging_api.cc

 // Copyright (c) 2012 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/extensions/api/push_messaging/push_messaging_api.h"
 
 #include <set>
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/string_number_conversions.h"
 #include "base/values.h"
+#include "chrome/browser/extensions/api/push_messaging/push_messaging_api_factory.h"
 #include "chrome/browser/extensions/api/push_messaging/push_messaging_invalidation_handler.h"
 #include "chrome/browser/extensions/event_names.h"
 #include "chrome/browser/extensions/event_router.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/signin/token_service.h"
 #include "chrome/browser/signin/token_service_factory.h"
 #include "chrome/browser/sync/profile_sync_service.h"
 #include "chrome/browser/sync/profile_sync_service_factory.h"
@@ skipping 45 matching lines @@
   // Register for extension load/unload as well, so we can update any
   // registrations as appropriate.
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_LOADED,
                  content::Source<Profile>(profile_->GetOriginalProfile()));
   registrar_.Add(this, chrome::NOTIFICATION_EXTENSION_UNLOADED,
                  content::Source<Profile>(profile_->GetOriginalProfile()));
 }
 
 PushMessagingEventRouter::~PushMessagingEventRouter() {}
 
-void PushMessagingEventRouter::Shutdown() {
-  // We need an explicit Shutdown() due to the dependencies among the various
-  // ProfileKeyedServices. ProfileSyncService depends on ExtensionSystem, so
-  // it is destroyed before us in the destruction phase of Profile shutdown.
-  // As a result, we need to drop any references to it in the Shutdown() phase
-  // instead.
-  handler_.reset();
-}
-
 void PushMessagingEventRouter::SetMapperForTest(
     scoped_ptr<PushMessagingInvalidationMapper> mapper) {
   handler_ = mapper.Pass();
 }
 
 void PushMessagingEventRouter::TriggerMessageForTest(
     const std::string& extension_id,
     int subchannel,
     const std::string& payload) {
   OnMessage(extension_id, subchannel, payload);
@@ skipping 185 matching lines @@
   std::string error_text = error.error_message();
   // If the error message is blank, see if we can set it from the state.
   if (error_text.empty() &&
       (0 != error.state())) {
     error_text = base::IntToString(error.state());
   }
 
   ReportResult(std::string(), error_text);
 }
 
+PushMessagingAPI::PushMessagingAPI(Profile* profile)
+    : profile_(profile) {
+  ExtensionSystem::Get(profile_)->event_router()->RegisterObserver(
+      this, event_names::kOnPushMessage);
+}
+
+PushMessagingAPI::~PushMessagingAPI() {
+}
+
+// static
+PushMessagingAPI* PushMessagingAPI::Get(Profile* profile) {
+  return PushMessagingAPIFactory::GetForProfile(profile);
+}
+
+void PushMessagingAPI::Shutdown() {
+  // It's safe to call UnregisterObserver more than once.

[akalin, 2012/12/12 21:39:15]

This comment could be clearer.  How about:

// UnregisterObserver() may have already been called in InitializeEventRouter(),
but it is safe to call it more than once.

[Joe Thomas, 2012/12/13 08:34:43]

Done.

+  // UnregisterObserver would have already called when the listener
+  // got added.
+  ExtensionSystem::Get(profile_)->event_router()->UnregisterObserver(this);
+  push_messaging_event_router_.reset();
+}
+
+void PushMessagingAPI::OnListenerAdded(
+    const extensions::EventListenerInfo& details) {
+  InitializeEventRouter();
+}
+
+void PushMessagingAPI::InitializeEventRouterForTest() {
+  InitializeEventRouter();
+}
+
+PushMessagingEventRouter* PushMessagingAPI::GetEventRouterForTest() {
+  return push_messaging_event_router_.get();
+}
+
+void PushMessagingAPI::InitializeEventRouter() {
+  DCHECK(!push_messaging_event_router_.get());
+  push_messaging_event_router_.reset(new PushMessagingEventRouter(profile_));
+  ExtensionSystem::Get(profile_)->event_router()->UnregisterObserver(this);
+}
+
 }  // namespace extensions