Reland 166821 - Lazy initialization for ProcessesEventRouter.

chrome/browser/extensions/api/processes/processes_api.cc

Index: chrome/browser/extensions/api/processes/processes_api.cc
diff --git a/chrome/browser/extensions/api/processes/processes_api.cc b/chrome/browser/extensions/api/processes/processes_api.cc
index 6c10f6e17f4bb27b79aed8db9b7f00997a59bc2d..bf3c1154d5f16490c55114eabac93cec85a0a9b8 100644
--- a/chrome/browser/extensions/api/processes/processes_api.cc
+++ b/chrome/browser/extensions/api/processes/processes_api.cc
@@ -13,6 +13,7 @@
 #include "base/values.h"
 
 #include "chrome/browser/extensions/api/processes/processes_api_constants.h"
+#include "chrome/browser/extensions/api/processes/processes_api_factory.h"
 #include "chrome/browser/extensions/api/tabs/tabs_constants.h"
 #include "chrome/browser/extensions/event_router.h"
 #include "chrome/browser/extensions/extension_function_util.h"
@@ -212,12 +213,9 @@ void AddMemoryDetails(DictionaryValue* result,
 
 }  // namespace
 
-ProcessesEventRouter* ProcessesEventRouter::GetInstance() {
-  return Singleton<ProcessesEventRouter>::get();
-}
-
-ProcessesEventRouter::ProcessesEventRouter()
-    : listeners_(0),
+ProcessesEventRouter::ProcessesEventRouter(Profile* profile)
+    : profile_(profile),
+      listeners_(0),
       task_manager_listening_(false) {
 #if defined(ENABLE_TASK_MANAGER)
   model_ = TaskManager::GetInstance()->model();
@@ -244,10 +242,6 @@ ProcessesEventRouter::~ProcessesEventRouter() {
 #endif  // defined(ENABLE_TASK_MANAGER)
 }
 
-void ProcessesEventRouter::ObserveProfile(Profile* profile) {
-  profiles_.insert(profile);
-}
-
 void ProcessesEventRouter::ListenerAdded() {
 #if defined(ENABLE_TASK_MANAGER)
   // The task manager has its own ref count to balance other callers of
@@ -323,7 +317,7 @@ void ProcessesEventRouter::OnItemsAdded(int start, int length) {
 
   args->Append(process);
 
-  NotifyProfiles(keys::kOnCreated, args.Pass());
+  DispatchEvent(keys::kOnCreated, args.Pass());
 #endif  // defined(ENABLE_TASK_MANAGER)
 }
 
@@ -370,7 +364,7 @@ void ProcessesEventRouter::OnItemsChanged(int start, int length) {
 
     scoped_ptr<ListValue> args(new ListValue());
     args->Append(processes);
-    NotifyProfiles(keys::kOnUpdated, args.Pass());
+    DispatchEvent(keys::kOnUpdated, args.Pass());
   }
 
   if (updated_memory) {
@@ -389,7 +383,7 @@ void ProcessesEventRouter::OnItemsChanged(int start, int length) {
 
     scoped_ptr<ListValue> args(new ListValue());
     args->Append(processes);
-    NotifyProfiles(keys::kOnUpdatedWithMemory, args.Pass());
+    DispatchEvent(keys::kOnUpdatedWithMemory, args.Pass());
   }
 #endif  // defined(ENABLE_TASK_MANAGER)
 }
@@ -418,7 +412,7 @@ void ProcessesEventRouter::OnItemsToBeRemoved(int start, int length) {
   // Third arg: The exit code for the process.
   args->Append(Value::CreateIntegerValue(0));
 
-  NotifyProfiles(keys::kOnExited, args.Pass());
+  DispatchEvent(keys::kOnExited, args.Pass());
 #endif  // defined(ENABLE_TASK_MANAGER)
 }
 
@@ -448,7 +442,7 @@ void ProcessesEventRouter::ProcessHangEvent(content::RenderWidgetHost* widget) {
   scoped_ptr<ListValue> args(new ListValue());
   args->Append(process);
 
-  NotifyProfiles(keys::kOnUnresponsive, args.Pass());
+  DispatchEvent(keys::kOnUnresponsive, args.Pass());
 #endif  // defined(ENABLE_TASK_MANAGER)
 }
 
@@ -468,49 +462,65 @@ void ProcessesEventRouter::ProcessClosedEvent(
   // Third arg: The exit code for the process.
   args->Append(Value::CreateIntegerValue(details->exit_code));
 
-  NotifyProfiles(keys::kOnExited, args.Pass());
+  DispatchEvent(keys::kOnExited, args.Pass());
 #endif  // defined(ENABLE_TASK_MANAGER)
 }
 
-void ProcessesEventRouter::DispatchEvent(Profile* profile,
-                                         const char* event_name,
+void ProcessesEventRouter::DispatchEvent(const char* event_name,
                                          scoped_ptr<ListValue> event_args) {
-  if (profile && extensions::ExtensionSystem::Get(profile)->event_router()) {
-    extensions::ExtensionSystem::Get(profile)->event_router()->
+  if (extensions::ExtensionSystem::Get(profile_)->event_router()) {
+    extensions::ExtensionSystem::Get(profile_)->event_router()->
         DispatchEventToRenderers(event_name, event_args.Pass(), NULL, GURL(),
                                  extensions::EventFilteringInfo());
   }
 }
 
-void ProcessesEventRouter::NotifyProfiles(const char* event_name,
-                                          scoped_ptr<ListValue> event_args) {
-  for (ProfileSet::iterator it = profiles_.begin();
-       it != profiles_.end(); ++it) {
-    Profile* profile = *it;
-    scoped_ptr<ListValue> event_args_copy(event_args->DeepCopy());
-    DispatchEvent(profile, event_name, event_args_copy.Pass());
-  }
-}
-
-// In order to determine whether there are any listeners for the event of
-// interest, we need to ask each profile whether it has one registered.
-// We only need to look for the profiles that have registered with the
-// this extension API.
 bool ProcessesEventRouter::HasEventListeners(const std::string& event_name) {
-  for (ProfileSet::iterator it = profiles_.begin();
-       it != profiles_.end(); ++it) {
-    Profile* profile = *it;
-    extensions::EventRouter* router =
-        extensions::ExtensionSystem::Get(profile)->event_router();
-    if (!router)
-      continue;
-
-    if (router->HasEventListener(event_name))
+  extensions::EventRouter* router =
+      extensions::ExtensionSystem::Get(profile_)->event_router();
+    if (router && router->HasEventListener(event_name))
       return true;
-  }
   return false;
 }
 
+ProcessesAPI::ProcessesAPI(Profile* profile) : profile_(profile) {
+  ExtensionSystem::Get(profile_)->event_router()->RegisterObserver(
+      this, processes_api_constants::kOnUpdated);
+  ExtensionSystem::Get(profile_)->event_router()->RegisterObserver(
+      this, processes_api_constants::kOnUpdatedWithMemory);
+}
+
+ProcessesAPI::~ProcessesAPI() {
+}
+
+void ProcessesAPI::Shutdown() {
+  ExtensionSystem::Get(profile_)->event_router()->UnregisterObserver(this);
+}
+
+// static
+ProcessesAPI* ProcessesAPI::Get(Profile* profile) {
+  return ProcessesAPIFactory::GetForProfile(profile);
+}
+
+ProcessesEventRouter* ProcessesAPI::processes_event_router() {
+  if (!processes_event_router_)
+    processes_event_router_.reset(new ProcessesEventRouter(profile_));
+  return processes_event_router_.get();
+}
+
+void ProcessesAPI::OnListenerAdded(const std::string& event_name) {
+  // We lazily tell the TaskManager to start updating when listeners to the
+  // processes.onUpdated or processes.onUpdatedWithMemory events arrive.
+  processes_event_router()->ListenerAdded();
+}
+
+void ProcessesAPI::OnListenerRemoved(const std::string& event_name) {
+  // If a processes.onUpdated or processes.onUpdatedWithMemory event listener
+  // is removed (or a process with one exits), then we let the extension API
+  // know that it has one fewer listener.
+  processes_event_router()->ListenerRemoved();
+}
+
 GetProcessIdForTabFunction::GetProcessIdForTabFunction() : tab_id_(-1) {
 }
 
@@ -526,14 +536,16 @@ bool GetProcessIdForTabFunction::RunImpl() {
   // which will invoke the callback once we have returned from this function.
   // Otherwise, wait for the notification that the task manager is done with
   // the data gathering.
-  if (ProcessesEventRouter::GetInstance()->is_task_manager_listening()) {
+  if (ProcessesAPI::Get(profile_)->processes_event_router()->
+      is_task_manager_listening()) {
     MessageLoop::current()->PostTask(FROM_HERE, base::Bind(
         &GetProcessIdForTabFunction::GetProcessIdForTab, this));
   } else {
     registrar_.Add(this,
                    chrome::NOTIFICATION_TASK_MANAGER_CHILD_PROCESSES_DATA_READY,
                    content::NotificationService::AllSources());
-    ProcessesEventRouter::GetInstance()->StartTaskManagerListening();
+    ProcessesAPI::Get(profile_)->processes_event_router()->
+        StartTaskManagerListening();
   }
 
   return true;
@@ -587,14 +599,16 @@ bool TerminateFunction::RunImpl() {
   // which will invoke the callback once we have returned from this function.
   // Otherwise, wait for the notification that the task manager is done with
   // the data gathering.
-  if (ProcessesEventRouter::GetInstance()->is_task_manager_listening()) {
+  if (ProcessesAPI::Get(profile_)->processes_event_router()->
+      is_task_manager_listening()) {
     MessageLoop::current()->PostTask(FROM_HERE, base::Bind(
         &TerminateFunction::TerminateProcess, this));
   } else {
     registrar_.Add(this,
                    chrome::NOTIFICATION_TASK_MANAGER_CHILD_PROCESSES_DATA_READY,
                    content::NotificationService::AllSources());
-    ProcessesEventRouter::GetInstance()->StartTaskManagerListening();
+    ProcessesAPI::Get(profile_)->processes_event_router()->
+        StartTaskManagerListening();
   }
 
   return true;
@@ -673,14 +687,16 @@ bool GetProcessInfoFunction::RunImpl() {
   // which will invoke the callback once we have returned from this function.
   // Otherwise, wait for the notification that the task manager is done with
   // the data gathering.
-  if (ProcessesEventRouter::GetInstance()->is_task_manager_listening()) {
+  if (ProcessesAPI::Get(profile_)->processes_event_router()->
+      is_task_manager_listening()) {
     MessageLoop::current()->PostTask(FROM_HERE, base::Bind(
         &GetProcessInfoFunction::GatherProcessInfo, this));
   } else {
     registrar_.Add(this,
                    chrome::NOTIFICATION_TASK_MANAGER_CHILD_PROCESSES_DATA_READY,
                    content::NotificationService::AllSources());
-    ProcessesEventRouter::GetInstance()->StartTaskManagerListening();
+    ProcessesAPI::Get(profile_)->processes_event_router()->
+        StartTaskManagerListening();
   }
   return true;