SystemInfo API: Fix SystemInfoEventRouter initialization code.

chrome/browser/extensions/api/system_info/system_info_api.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/extensions/api/system_info/system_info_api.h"
 
 #include <set>
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
@@ skipping 50 matching lines @@
   virtual void OnDisplayAdded(const gfx::Display& new_display) OVERRIDE;
   virtual void OnDisplayRemoved(const gfx::Display& old_display) OVERRIDE;
 
   // RemovableStorageObserver implementation.
   virtual void OnRemovableStorageAttached(const StorageInfo& info) OVERRIDE;
   virtual void OnRemovableStorageDetached(const StorageInfo& info) OVERRIDE;
 
   // Called from any thread to dispatch the systemInfo event to all extension
   // processes cross multiple profiles.
   void DispatchEvent(const std::string& event_name,
-      scoped_ptr<base::ListValue> args);
+                     scoped_ptr<base::ListValue> args);
 
   // Called to dispatch the systemInfo.display.onDisplayChanged event.
   void OnDisplayChanged();
 
   // Used to record the event names being watched.
   std::multiset<std::string> watching_event_set_;
 
   DISALLOW_COPY_AND_ASSIGN(SystemInfoEventRouter);
 };
 
 static base::LazyInstance<SystemInfoEventRouter>::Leaky
   g_system_info_event_router = LAZY_INSTANCE_INITIALIZER;
 
 // static
 SystemInfoEventRouter* SystemInfoEventRouter::GetInstance() {
   return g_system_info_event_router.Pointer();
 }
 
 SystemInfoEventRouter::SystemInfoEventRouter() {
   StorageMonitor::GetInstance()->AddObserver(this);
-  StorageMonitor::GetInstance()->EnsureInitialized(base::Closure());
 }
 
 SystemInfoEventRouter::~SystemInfoEventRouter() {
   if (StorageMonitor* storage_monitor = StorageMonitor::GetInstance())
     storage_monitor->RemoveObserver(this);
 }
 
 void SystemInfoEventRouter::AddEventListener(const std::string& event_name) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   watching_event_set_.insert(event_name);
   if (watching_event_set_.count(event_name) > 1)
     return;
 
   // For systemInfo.display event.
   if (IsDisplayChangedEvent(event_name)) {
 #if defined(USE_ASH)
     ash::Shell::GetScreen()->AddObserver(this);
 #endif
   }
 }
 
-void SystemInfoEventRouter::RemoveEventListener(
-    const std::string& event_name) {
+void SystemInfoEventRouter::RemoveEventListener(const std::string& event_name) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   std::multiset<std::string>::iterator it =
       watching_event_set_.find(event_name);
   if (it != watching_event_set_.end())
     watching_event_set_.erase(it);
 
   if (watching_event_set_.count(event_name) > 0)
     return;
 
@@ skipping 38 matching lines @@
 void SystemInfoEventRouter::OnDisplayChanged() {
   scoped_ptr<base::ListValue> args(new base::ListValue());
   DispatchEvent(system_display::OnDisplayChanged::kEventName, args.Pass());
 }
 
 void SystemInfoEventRouter::DispatchEvent(const std::string& event_name,
                                           scoped_ptr<base::ListValue> args) {
   g_browser_process->extension_event_router_forwarder()->
       BroadcastEventToRenderers(event_name, args.Pass(), GURL());
 }
 

[Haojian Wu, 2014/01/16 06:53:27]

Some performance concerns: everytime we add an systemInfo event, we will invoke
StorageMonitor::EnsureInitialized to make sure StorageMonitor is constructed.
The type of systemInfo event is including display, so when we add display event,
the checking is unnecessay.

[Lei Zhang, 2014/01/16 23:24:11]

See patch set 2.

+void AddEventListener(const std::string& event_name) {
+  DCHECK(StorageMonitor::GetInstance()->IsInitialized());
+  SystemInfoEventRouter::GetInstance()->AddEventListener(event_name);
+}
+
+void RemoveEventListener(const std::string& event_name) {
+  DCHECK(StorageMonitor::GetInstance()->IsInitialized());
+  SystemInfoEventRouter::GetInstance()->RemoveEventListener(event_name);
+}
+
 }  // namespace
 
 static base::LazyInstance<ProfileKeyedAPIFactory<SystemInfoAPI> >
     g_factory = LAZY_INSTANCE_INITIALIZER;
 
 // static
 ProfileKeyedAPIFactory<SystemInfoAPI>* SystemInfoAPI::GetFactoryInstance() {
   return &g_factory.Get();
 }
 
 SystemInfoAPI::SystemInfoAPI(Profile* profile) : profile_(profile) {
   ExtensionSystem::Get(profile_)->event_router()->RegisterObserver(
       this, system_storage::OnAttached::kEventName);
   ExtensionSystem::Get(profile_)->event_router()->RegisterObserver(
       this, system_storage::OnDetached::kEventName);
   ExtensionSystem::Get(profile_)->event_router()->RegisterObserver(
       this, system_display::OnDisplayChanged::kEventName);
 }
 
 SystemInfoAPI::~SystemInfoAPI() {
 }
 
 void SystemInfoAPI::Shutdown() {
   ExtensionSystem::Get(profile_)->event_router()->UnregisterObserver(this);
 }
 
 void SystemInfoAPI::OnListenerAdded(const EventListenerInfo& details) {
-  SystemInfoEventRouter::GetInstance()->AddEventListener(details.event_name);
+  StorageMonitor::GetInstance()->EnsureInitialized(
+      base::Bind(&AddEventListener, details.event_name));
 }
 
 void SystemInfoAPI::OnListenerRemoved(const EventListenerInfo& details) {
-  SystemInfoEventRouter::GetInstance()->RemoveEventListener(details.event_name);
+  StorageMonitor::GetInstance()->EnsureInitialized(
+      base::Bind(&RemoveEventListener, details.event_name));
 }
 
 }  // namespace extensions