extensions/browser/event_router.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "extensions/browser/event_router.h"
   6
   7 #include <utility>
   8
   9 #include "base/atomic_sequence_num.h"
  10 #include "base/bind.h"
  11 #include "base/command_line.h"
  12 #include "base/lazy_instance.h"
  13 #include "base/message_loop/message_loop.h"
  14 #include "base/stl_util.h"
  15 #include "base/values.h"
  16 #include "content/public/browser/notification_service.h"
  17 #include "content/public/browser/render_process_host.h"
  18 #include "extensions/browser/api_activity_monitor.h"
  19 #include "extensions/browser/extension_host.h"
  20 #include "extensions/browser/extension_prefs.h"
  21 #include "extensions/browser/extension_registry.h"
  22 #include "extensions/browser/extension_system.h"
  23 #include "extensions/browser/extensions_browser_client.h"
  24 #include "extensions/browser/lazy_background_task_queue.h"
  25 #include "extensions/browser/notification_types.h"
  26 #include "extensions/browser/process_manager.h"
  27 #include "extensions/browser/process_map.h"
  28 #include "extensions/common/extension.h"
  29 #include "extensions/common/extension_api.h"
  30 #include "extensions/common/extension_messages.h"
  31 #include "extensions/common/extension_urls.h"
  32 #include "extensions/common/features/feature.h"
  33 #include "extensions/common/features/feature_provider.h"
  34 #include "extensions/common/manifest_handlers/background_info.h"
  35 #include "extensions/common/manifest_handlers/incognito_info.h"
  36 #include "extensions/common/permissions/permissions_data.h"
  37
  38 using base::DictionaryValue;
  39 using base::ListValue;
  40 using content::BrowserContext;
  41 using content::BrowserThread;
  42
  43 namespace extensions {
  44
  45 namespace {
  46
  47 void DoNothing(ExtensionHost* host) {}
  48
  49 // A dictionary of event names to lists of filters that this extension has
  50 // registered from its lazy background page.
  51 const char kFilteredEvents[] = "filtered_events";
  52
  53 // Sends a notification about an event to the API activity monitor and the
  54 // ExtensionHost for |extension_id| on the UI thread. Can be called from any
  55 // thread.
  56 void NotifyEventDispatched(void* browser_context_id,
  57                            const std::string& extension_id,
  58                            const std::string& event_name,
  59                            scoped_ptr<ListValue> args) {
  60   // The ApiActivityMonitor can only be accessed from the UI thread.
  61   if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
  62     BrowserThread::PostTask(
  63         BrowserThread::UI, FROM_HERE,
  64         base::Bind(&NotifyEventDispatched, browser_context_id, extension_id,
  65                    event_name, base::Passed(&args)));
  66     return;
  67   }
  68
  69   // Notify the ApiActivityMonitor about the event dispatch.
  70   BrowserContext* context = static_cast<BrowserContext*>(browser_context_id);
  71   if (!ExtensionsBrowserClient::Get()->IsValidContext(context))
  72     return;
  73   ApiActivityMonitor* monitor =
  74       ExtensionsBrowserClient::Get()->GetApiActivityMonitor(context);
  75   if (monitor)
  76     monitor->OnApiEventDispatched(extension_id, event_name, args.Pass());
  77 }
  78
  79 // A global identifier used to distinguish extension events.
  80 base::StaticAtomicSequenceNumber g_extension_event_id;
  81
  82 }  // namespace
  83
  84 const char EventRouter::kRegisteredEvents[] = "events";
  85
  86 struct EventRouter::ListenerProcess {
  87   content::RenderProcessHost* process;
  88   std::string extension_id;
  89
  90   ListenerProcess(content::RenderProcessHost* process,
  91                   const std::string& extension_id)
  92       : process(process), extension_id(extension_id) {}
  93
  94   bool operator<(const ListenerProcess& that) const {
  95     if (process < that.process)
  96       return true;
  97     if (process == that.process && extension_id < that.extension_id)
  98       return true;
  99     return false;
 100   }
 101 };
 102
 103 // static
 104 void EventRouter::DispatchExtensionMessage(IPC::Sender* ipc_sender,
 105                                            void* browser_context_id,
 106                                            const std::string& extension_id,
 107                                            int event_id,
 108                                            const std::string& event_name,
 109                                            ListValue* event_args,
 110                                            UserGestureState user_gesture,
 111                                            const EventFilteringInfo& info) {
 112   NotifyEventDispatched(browser_context_id, extension_id, event_name,
 113                         make_scoped_ptr(event_args->DeepCopy()));
 114
 115   // TODO(chirantan): Make event dispatch a separate IPC so that it doesn't
 116   // piggyback off MessageInvoke, which is used for other things.
 117   ListValue args;
 118   args.Set(0, new base::StringValue(event_name));
 119   args.Set(1, event_args);
 120   args.Set(2, info.AsValue().release());
 121   args.Set(3, new base::FundamentalValue(event_id));
 122   ipc_sender->Send(new ExtensionMsg_MessageInvoke(
 123       MSG_ROUTING_CONTROL,
 124       extension_id,
 125       kEventBindings,
 126       "dispatchEvent",
 127       args,
 128       user_gesture == USER_GESTURE_ENABLED));
 129
 130   // DispatchExtensionMessage does _not_ take ownership of event_args, so we
 131   // must ensure that the destruction of args does not attempt to free it.
 132   scoped_ptr<base::Value> removed_event_args;
 133   args.Remove(1, &removed_event_args);
 134   ignore_result(removed_event_args.release());
 135 }
 136
 137 // static
 138 EventRouter* EventRouter::Get(content::BrowserContext* browser_context) {
 139   return ExtensionSystem::Get(browser_context)->event_router();
 140 }
 141
 142 // static
 143 std::string EventRouter::GetBaseEventName(const std::string& full_event_name) {
 144   size_t slash_sep = full_event_name.find('/');
 145   return full_event_name.substr(0, slash_sep);
 146 }
 147
 148 // static
 149 void EventRouter::DispatchEvent(IPC::Sender* ipc_sender,
 150                                 void* browser_context_id,
 151                                 const std::string& extension_id,
 152                                 const std::string& event_name,
 153                                 scoped_ptr<ListValue> event_args,
 154                                 UserGestureState user_gesture,
 155                                 const EventFilteringInfo& info) {
 156   int event_id = g_extension_event_id.GetNext();
 157
 158   DispatchExtensionMessage(ipc_sender, browser_context_id, extension_id,
 159                            event_id, event_name, event_args.get(), user_gesture,
 160                            info);
 161
 162   BrowserThread::PostTask(
 163       BrowserThread::UI, FROM_HERE,
 164       base::Bind(&EventRouter::IncrementInFlightEventsOnUI, browser_context_id,
 165                  extension_id, event_id, event_name));
 166 }
 167
 168 EventRouter::EventRouter(BrowserContext* browser_context,
 169                          ExtensionPrefs* extension_prefs)
 170     : browser_context_(browser_context),
 171       extension_prefs_(extension_prefs),
 172       extension_registry_observer_(this),
 173       listeners_(this) {
 174   registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_TERMINATED,
 175                  content::NotificationService::AllSources());
 176   registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_CLOSED,
 177                  content::NotificationService::AllSources());
 178   registrar_.Add(this,
 179                  extensions::NOTIFICATION_EXTENSION_ENABLED,
 180                  content::Source<BrowserContext>(browser_context_));
 181   extension_registry_observer_.Add(ExtensionRegistry::Get(browser_context_));
 182 }
 183
 184 EventRouter::~EventRouter() {}
 185
 186 void EventRouter::AddEventListener(const std::string& event_name,
 187                                    content::RenderProcessHost* process,
 188                                    const std::string& extension_id) {
 189   listeners_.AddListener(EventListener::ForExtension(
 190       event_name, extension_id, process, scoped_ptr<DictionaryValue>()));
 191 }
 192
 193 void EventRouter::RemoveEventListener(const std::string& event_name,
 194                                       content::RenderProcessHost* process,
 195                                       const std::string& extension_id) {
 196   scoped_ptr<EventListener> listener = EventListener::ForExtension(
 197       event_name, extension_id, process, scoped_ptr<DictionaryValue>());
 198   listeners_.RemoveListener(listener.get());
 199 }
 200
 201 void EventRouter::AddEventListenerForURL(const std::string& event_name,
 202                                          content::RenderProcessHost* process,
 203                                          const GURL& listener_url) {
 204   listeners_.AddListener(EventListener::ForURL(
 205       event_name, listener_url, process, scoped_ptr<DictionaryValue>()));
 206 }
 207
 208 void EventRouter::RemoveEventListenerForURL(const std::string& event_name,
 209                                             content::RenderProcessHost* process,
 210                                             const GURL& listener_url) {
 211   scoped_ptr<EventListener> listener = EventListener::ForURL(
 212       event_name, listener_url, process, scoped_ptr<DictionaryValue>());
 213   listeners_.RemoveListener(listener.get());
 214 }
 215
 216 void EventRouter::RegisterObserver(Observer* observer,
 217                                    const std::string& event_name) {
 218   // Observing sub-event names like "foo.onBar/123" is not allowed.
 219   DCHECK(event_name.find('/') == std::string::npos);
 220   observers_[event_name] = observer;
 221 }
 222
 223 void EventRouter::UnregisterObserver(Observer* observer) {
 224   std::vector<ObserverMap::iterator> iters_to_remove;
 225   for (ObserverMap::iterator iter = observers_.begin();
 226        iter != observers_.end(); ++iter) {
 227     if (iter->second == observer)
 228       iters_to_remove.push_back(iter);
 229   }
 230   for (size_t i = 0; i < iters_to_remove.size(); ++i)
 231     observers_.erase(iters_to_remove[i]);
 232 }
 233
 234 void EventRouter::OnListenerAdded(const EventListener* listener) {
 235   const EventListenerInfo details(listener->event_name(),
 236                                   listener->extension_id(),
 237                                   listener->listener_url(),
 238                                   listener->GetBrowserContext());
 239   std::string base_event_name = GetBaseEventName(listener->event_name());
 240   ObserverMap::iterator observer = observers_.find(base_event_name);
 241   if (observer != observers_.end())
 242     observer->second->OnListenerAdded(details);
 243 }
 244
 245 void EventRouter::OnListenerRemoved(const EventListener* listener) {
 246   const EventListenerInfo details(listener->event_name(),
 247                                   listener->extension_id(),
 248                                   listener->listener_url(),
 249                                   listener->GetBrowserContext());
 250   std::string base_event_name = GetBaseEventName(listener->event_name());
 251   ObserverMap::iterator observer = observers_.find(base_event_name);
 252   if (observer != observers_.end())
 253     observer->second->OnListenerRemoved(details);
 254 }
 255
 256 void EventRouter::AddLazyEventListener(const std::string& event_name,
 257                                        const std::string& extension_id) {
 258   bool is_new = listeners_.AddListener(EventListener::ForExtension(
 259       event_name, extension_id, NULL, scoped_ptr<DictionaryValue>()));
 260
 261   if (is_new) {
 262     std::set<std::string> events = GetRegisteredEvents(extension_id);
 263     bool prefs_is_new = events.insert(event_name).second;
 264     if (prefs_is_new)
 265       SetRegisteredEvents(extension_id, events);
 266   }
 267 }
 268
 269 void EventRouter::RemoveLazyEventListener(const std::string& event_name,
 270                                           const std::string& extension_id) {
 271   scoped_ptr<EventListener> listener = EventListener::ForExtension(
 272       event_name, extension_id, NULL, scoped_ptr<DictionaryValue>());
 273   bool did_exist = listeners_.RemoveListener(listener.get());
 274
 275   if (did_exist) {
 276     std::set<std::string> events = GetRegisteredEvents(extension_id);
 277     bool prefs_did_exist = events.erase(event_name) > 0;
 278     DCHECK(prefs_did_exist);
 279     SetRegisteredEvents(extension_id, events);
 280   }
 281 }
 282
 283 void EventRouter::AddFilteredEventListener(const std::string& event_name,
 284                                            content::RenderProcessHost* process,
 285                                            const std::string& extension_id,
 286                                            const base::DictionaryValue& filter,
 287                                            bool add_lazy_listener) {
 288   listeners_.AddListener(EventListener::ForExtension(
 289       event_name,
 290       extension_id,
 291       process,
 292       scoped_ptr<DictionaryValue>(filter.DeepCopy())));
 293
 294   if (add_lazy_listener) {
 295     bool added = listeners_.AddListener(EventListener::ForExtension(
 296         event_name,
 297         extension_id,
 298         NULL,
 299         scoped_ptr<DictionaryValue>(filter.DeepCopy())));
 300
 301     if (added)
 302       AddFilterToEvent(event_name, extension_id, &filter);
 303   }
 304 }
 305
 306 void EventRouter::RemoveFilteredEventListener(
 307     const std::string& event_name,
 308     content::RenderProcessHost* process,
 309     const std::string& extension_id,
 310     const base::DictionaryValue& filter,
 311     bool remove_lazy_listener) {
 312   scoped_ptr<EventListener> listener = EventListener::ForExtension(
 313       event_name,
 314       extension_id,
 315       process,
 316       scoped_ptr<DictionaryValue>(filter.DeepCopy()));
 317
 318   listeners_.RemoveListener(listener.get());
 319
 320   if (remove_lazy_listener) {
 321     listener->MakeLazy();
 322     bool removed = listeners_.RemoveListener(listener.get());
 323
 324     if (removed)
 325       RemoveFilterFromEvent(event_name, extension_id, &filter);
 326   }
 327 }
 328
 329 bool EventRouter::HasEventListener(const std::string& event_name) {
 330   return listeners_.HasListenerForEvent(event_name);
 331 }
 332
 333 bool EventRouter::ExtensionHasEventListener(const std::string& extension_id,
 334                                             const std::string& event_name) {
 335   return listeners_.HasListenerForExtension(extension_id, event_name);
 336 }
 337
 338 bool EventRouter::HasEventListenerImpl(const ListenerMap& listener_map,
 339                                        const std::string& extension_id,
 340                                        const std::string& event_name) {
 341   ListenerMap::const_iterator it = listener_map.find(event_name);
 342   if (it == listener_map.end())
 343     return false;
 344
 345   const std::set<ListenerProcess>& listeners = it->second;
 346   if (extension_id.empty())
 347     return !listeners.empty();
 348
 349   for (std::set<ListenerProcess>::const_iterator listener = listeners.begin();
 350        listener != listeners.end(); ++listener) {
 351     if (listener->extension_id == extension_id)
 352       return true;
 353   }
 354   return false;
 355 }
 356
 357 std::set<std::string> EventRouter::GetRegisteredEvents(
 358     const std::string& extension_id) {
 359   std::set<std::string> events;
 360   const ListValue* events_value = NULL;
 361
 362   if (!extension_prefs_ ||
 363       !extension_prefs_->ReadPrefAsList(
 364            extension_id, kRegisteredEvents, &events_value)) {
 365     return events;
 366   }
 367
 368   for (size_t i = 0; i < events_value->GetSize(); ++i) {
 369     std::string event;
 370     if (events_value->GetString(i, &event))
 371       events.insert(event);
 372   }
 373   return events;
 374 }
 375
 376 void EventRouter::SetRegisteredEvents(const std::string& extension_id,
 377                                       const std::set<std::string>& events) {
 378   ListValue* events_value = new ListValue;
 379   for (std::set<std::string>::const_iterator iter = events.begin();
 380        iter != events.end(); ++iter) {
 381     events_value->Append(new base::StringValue(*iter));
 382   }
 383   extension_prefs_->UpdateExtensionPref(
 384       extension_id, kRegisteredEvents, events_value);
 385 }
 386
 387 void EventRouter::AddFilterToEvent(const std::string& event_name,
 388                                    const std::string& extension_id,
 389                                    const DictionaryValue* filter) {
 390   ExtensionPrefs::ScopedDictionaryUpdate update(
 391       extension_prefs_, extension_id, kFilteredEvents);
 392   DictionaryValue* filtered_events = update.Get();
 393   if (!filtered_events)
 394     filtered_events = update.Create();
 395
 396   ListValue* filter_list = NULL;
 397   if (!filtered_events->GetList(event_name, &filter_list)) {
 398     filter_list = new ListValue;
 399     filtered_events->SetWithoutPathExpansion(event_name, filter_list);
 400   }
 401
 402   filter_list->Append(filter->DeepCopy());
 403 }
 404
 405 void EventRouter::RemoveFilterFromEvent(const std::string& event_name,
 406                                         const std::string& extension_id,
 407                                         const DictionaryValue* filter) {
 408   ExtensionPrefs::ScopedDictionaryUpdate update(
 409       extension_prefs_, extension_id, kFilteredEvents);
 410   DictionaryValue* filtered_events = update.Get();
 411   ListValue* filter_list = NULL;
 412   if (!filtered_events ||
 413       !filtered_events->GetListWithoutPathExpansion(event_name, &filter_list)) {
 414     return;
 415   }
 416
 417   for (size_t i = 0; i < filter_list->GetSize(); i++) {
 418     DictionaryValue* filter = NULL;
 419     CHECK(filter_list->GetDictionary(i, &filter));
 420     if (filter->Equals(filter)) {
 421       filter_list->Remove(i, NULL);
 422       break;
 423     }
 424   }
 425 }
 426
 427 const DictionaryValue* EventRouter::GetFilteredEvents(
 428     const std::string& extension_id) {
 429   const DictionaryValue* events = NULL;
 430   extension_prefs_->ReadPrefAsDictionary(
 431       extension_id, kFilteredEvents, &events);
 432   return events;
 433 }
 434
 435 void EventRouter::BroadcastEvent(scoped_ptr<Event> event) {
 436   DispatchEventImpl(std::string(), linked_ptr<Event>(event.release()));
 437 }
 438
 439 void EventRouter::DispatchEventToExtension(const std::string& extension_id,
 440                                            scoped_ptr<Event> event) {
 441   DCHECK(!extension_id.empty());
 442   DispatchEventImpl(extension_id, linked_ptr<Event>(event.release()));
 443 }
 444
 445 void EventRouter::DispatchEventWithLazyListener(const std::string& extension_id,
 446                                                 scoped_ptr<Event> event) {
 447   DCHECK(!extension_id.empty());
 448   std::string event_name = event->event_name;
 449   bool has_listener = ExtensionHasEventListener(extension_id, event_name);
 450   if (!has_listener)
 451     AddLazyEventListener(event_name, extension_id);
 452   DispatchEventToExtension(extension_id, event.Pass());
 453   if (!has_listener)
 454     RemoveLazyEventListener(event_name, extension_id);
 455 }
 456
 457 void EventRouter::DispatchEventImpl(const std::string& restrict_to_extension_id,
 458                                     const linked_ptr<Event>& event) {
 459   // We don't expect to get events from a completely different browser context.
 460   DCHECK(!event->restrict_to_browser_context ||
 461          ExtensionsBrowserClient::Get()->IsSameContext(
 462              browser_context_, event->restrict_to_browser_context));
 463
 464   std::set<const EventListener*> listeners(
 465       listeners_.GetEventListeners(*event));
 466
 467   std::set<EventDispatchIdentifier> already_dispatched;
 468
 469   // We dispatch events for lazy background pages first because attempting to do
 470   // so will cause those that are being suspended to cancel that suspension.
 471   // As canceling a suspension entails sending an event to the affected
 472   // background page, and as that event needs to be delivered before we dispatch
 473   // the event we are dispatching here, we dispatch to the lazy listeners here
 474   // first.
 475   for (std::set<const EventListener*>::iterator it = listeners.begin();
 476        it != listeners.end(); it++) {
 477     const EventListener* listener = *it;
 478     if (restrict_to_extension_id.empty() ||
 479         restrict_to_extension_id == listener->extension_id()) {
 480       if (listener->IsLazy()) {
 481         DispatchLazyEvent(listener->extension_id(), event, &already_dispatched);
 482       }
 483     }
 484   }
 485
 486   for (std::set<const EventListener*>::iterator it = listeners.begin();
 487        it != listeners.end(); it++) {
 488     const EventListener* listener = *it;
 489     if (restrict_to_extension_id.empty() ||
 490         restrict_to_extension_id == listener->extension_id()) {
 491       if (listener->process()) {
 492         EventDispatchIdentifier dispatch_id(listener->GetBrowserContext(),
 493                                             listener->extension_id());
 494         if (!ContainsKey(already_dispatched, dispatch_id)) {
 495           DispatchEventToProcess(listener->extension_id(),
 496                                  listener->listener_url(),
 497                                  listener->process(),
 498                                  event);
 499         }
 500       }
 501     }
 502   }
 503 }
 504
 505 void EventRouter::DispatchLazyEvent(
 506     const std::string& extension_id,
 507     const linked_ptr<Event>& event,
 508     std::set<EventDispatchIdentifier>* already_dispatched) {
 509   // Check both the original and the incognito browser context to see if we
 510   // should load a lazy bg page to handle the event. The latter case
 511   // occurs in the case of split-mode extensions.
 512   const Extension* extension =
 513       ExtensionRegistry::Get(browser_context_)->enabled_extensions().GetByID(
 514           extension_id);
 515   if (!extension)
 516     return;
 517
 518   if (MaybeLoadLazyBackgroundPageToDispatchEvent(
 519           browser_context_, extension, event)) {
 520     already_dispatched->insert(std::make_pair(browser_context_, extension_id));
 521   }
 522
 523   ExtensionsBrowserClient* browser_client = ExtensionsBrowserClient::Get();
 524   if (browser_client->HasOffTheRecordContext(browser_context_) &&
 525       IncognitoInfo::IsSplitMode(extension)) {
 526     BrowserContext* incognito_context =
 527         browser_client->GetOffTheRecordContext(browser_context_);
 528     if (MaybeLoadLazyBackgroundPageToDispatchEvent(
 529             incognito_context, extension, event)) {
 530       already_dispatched->insert(
 531           std::make_pair(incognito_context, extension_id));
 532     }
 533   }
 534 }
 535
 536 void EventRouter::DispatchEventToProcess(const std::string& extension_id,
 537                                          const GURL& listener_url,
 538                                          content::RenderProcessHost* process,
 539                                          const linked_ptr<Event>& event) {
 540   BrowserContext* listener_context = process->GetBrowserContext();
 541   ProcessMap* process_map = ProcessMap::Get(listener_context);
 542
 543   // NOTE: |extension| being NULL does not necessarily imply that this event
 544   // shouldn't be dispatched. Events can be dispatched to WebUI and webviews as
 545   // well.  It all depends on what GetMostLikelyContextType returns.
 546   const Extension* extension =
 547       ExtensionRegistry::Get(browser_context_)->enabled_extensions().GetByID(
 548           extension_id);
 549
 550   if (!extension && !extension_id.empty()) {
 551     // Trying to dispatch an event to an extension that doesn't exist. The
 552     // extension could have been removed, but we do not unregister it until the
 553     // extension process is unloaded.
 554     return;
 555   }
 556
 557   if (extension) {
 558     // Extension-specific checks.
 559     // Firstly, if the event is for a URL, the Extension must have permission
 560     // to access that URL.
 561     if (!event->event_url.is_empty() &&
 562         event->event_url.host() != extension->id() &&  // event for self is ok
 563         !extension->permissions_data()
 564              ->active_permissions()
 565              ->HasEffectiveAccessToURL(event->event_url)) {
 566       return;
 567     }
 568     // Secondly, if the event is for incognito mode, the Extension must be
 569     // enabled in incognito mode.
 570     if (!CanDispatchEventToBrowserContext(listener_context, extension, event)) {
 571       return;
 572     }
 573   }
 574
 575   Feature::Context target_context =
 576       process_map->GetMostLikelyContextType(extension, process->GetID());
 577
 578   // We shouldn't be dispatching an event to a webpage, since all such events
 579   // (e.g.  messaging) don't go through EventRouter.
 580   DCHECK_NE(Feature::WEB_PAGE_CONTEXT, target_context)
 581       << "Trying to dispatch event " << event->event_name << " to a webpage,"
 582       << " but this shouldn't be possible";
 583
 584   Feature::Availability availability =
 585       ExtensionAPI::GetSharedInstance()->IsAvailable(
 586           event->event_name, extension, target_context, listener_url);
 587   if (!availability.is_available()) {
 588     // It shouldn't be possible to reach here, because access is checked on
 589     // registration. However, for paranoia, check on dispatch as well.
 590     NOTREACHED() << "Trying to dispatch event " << event->event_name
 591                  << " which the target does not have access to: "
 592                  << availability.message();
 593     return;
 594   }
 595
 596   if (!event->will_dispatch_callback.is_null() &&
 597       !event->will_dispatch_callback.Run(listener_context, extension,
 598                                          event->event_args.get())) {
 599     return;
 600   }
 601
 602   int event_id = g_extension_event_id.GetNext();
 603   DispatchExtensionMessage(process, listener_context, extension_id, event_id,
 604                            event->event_name, event->event_args.get(),
 605                            event->user_gesture, event->filter_info);
 606
 607   if (extension) {
 608     IncrementInFlightEvents(listener_context, extension, event_id,
 609                             event->event_name);
 610   }
 611 }
 612
 613 bool EventRouter::CanDispatchEventToBrowserContext(
 614     BrowserContext* context,
 615     const Extension* extension,
 616     const linked_ptr<Event>& event) {
 617   // Is this event from a different browser context than the renderer (ie, an
 618   // incognito tab event sent to a normal process, or vice versa).
 619   bool cross_incognito = event->restrict_to_browser_context &&
 620                          context != event->restrict_to_browser_context;
 621   if (!cross_incognito)
 622     return true;
 623   return ExtensionsBrowserClient::Get()->CanExtensionCrossIncognito(
 624       extension, context);
 625 }
 626
 627 bool EventRouter::MaybeLoadLazyBackgroundPageToDispatchEvent(
 628     BrowserContext* context,
 629     const Extension* extension,
 630     const linked_ptr<Event>& event) {
 631   if (!CanDispatchEventToBrowserContext(context, extension, event))
 632     return false;
 633
 634   LazyBackgroundTaskQueue* queue = ExtensionSystem::Get(
 635       context)->lazy_background_task_queue();
 636   if (queue->ShouldEnqueueTask(context, extension)) {
 637     linked_ptr<Event> dispatched_event(event);
 638
 639     // If there's a dispatch callback, call it now (rather than dispatch time)
 640     // to avoid lifetime issues. Use a separate copy of the event args, so they
 641     // last until the event is dispatched.
 642     if (!event->will_dispatch_callback.is_null()) {
 643       dispatched_event.reset(event->DeepCopy());
 644       if (!dispatched_event->will_dispatch_callback.Run(
 645               context, extension, dispatched_event->event_args.get())) {
 646         // The event has been canceled.
 647         return true;
 648       }
 649       // Ensure we don't call it again at dispatch time.
 650       dispatched_event->will_dispatch_callback.Reset();
 651     }
 652
 653     queue->AddPendingTask(context, extension->id(),
 654                           base::Bind(&EventRouter::DispatchPendingEvent,
 655                                      base::Unretained(this), dispatched_event));
 656     return true;
 657   }
 658
 659   return false;
 660 }
 661
 662 // static
 663 void EventRouter::IncrementInFlightEventsOnUI(void* browser_context_id,
 664                                               const std::string& extension_id,
 665                                               int event_id,
 666                                               const std::string& event_name) {
 667   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 668   BrowserContext* browser_context =
 669       reinterpret_cast<BrowserContext*>(browser_context_id);
 670   if (!ExtensionsBrowserClient::Get()->IsValidContext(browser_context))
 671     return;
 672   EventRouter* event_router = EventRouter::Get(browser_context);
 673   if (!event_router)
 674     return;
 675   const Extension* extension =
 676       ExtensionRegistry::Get(browser_context)->enabled_extensions().GetByID(
 677           extension_id);
 678   if (!extension)
 679     return;
 680   event_router->IncrementInFlightEvents(browser_context, extension, event_id,
 681                                         event_name);
 682 }
 683
 684 void EventRouter::IncrementInFlightEvents(BrowserContext* context,
 685                                           const Extension* extension,
 686                                           int event_id,
 687                                           const std::string& event_name) {
 688   // TODO(chirantan): Turn this on once crbug.com/464513 is fixed.
 689   // DCHECK_CURRENTLY_ON(BrowserThread::UI);
 690
 691   // Only increment in-flight events if the lazy background page is active,
 692   // because that's the only time we'll get an ACK.
 693   if (BackgroundInfo::HasLazyBackgroundPage(extension)) {
 694     ProcessManager* pm = ProcessManager::Get(context);
 695     ExtensionHost* host = pm->GetBackgroundHostForExtension(extension->id());
 696     if (host) {
 697       pm->IncrementLazyKeepaliveCount(extension);
 698       host->OnBackgroundEventDispatched(event_name, event_id);
 699     }
 700   }
 701 }
 702
 703 void EventRouter::OnEventAck(BrowserContext* context,
 704                              const std::string& extension_id) {
 705   ProcessManager* pm = ProcessManager::Get(context);
 706   ExtensionHost* host = pm->GetBackgroundHostForExtension(extension_id);
 707   // The event ACK is routed to the background host, so this should never be
 708   // NULL.
 709   CHECK(host);
 710   // TODO(mpcomplete): We should never get this message unless
 711   // HasLazyBackgroundPage is true. Find out why we're getting it anyway.
 712   if (host->extension() &&
 713       BackgroundInfo::HasLazyBackgroundPage(host->extension()))
 714     pm->DecrementLazyKeepaliveCount(host->extension());
 715 }
 716
 717 void EventRouter::DispatchPendingEvent(const linked_ptr<Event>& event,
 718                                        ExtensionHost* host) {
 719   if (!host)
 720     return;
 721
 722   if (listeners_.HasProcessListener(host->render_process_host(),
 723                                     host->extension()->id())) {
 724     // URL events cannot be lazy therefore can't be pending, hence the GURL().
 725     DispatchEventToProcess(
 726         host->extension()->id(), GURL(), host->render_process_host(), event);
 727   }
 728 }
 729
 730 void EventRouter::Observe(int type,
 731                           const content::NotificationSource& source,
 732                           const content::NotificationDetails& details) {
 733   switch (type) {
 734     case content::NOTIFICATION_RENDERER_PROCESS_TERMINATED:
 735     case content::NOTIFICATION_RENDERER_PROCESS_CLOSED: {
 736       content::RenderProcessHost* renderer =
 737           content::Source<content::RenderProcessHost>(source).ptr();
 738       // Remove all event listeners associated with this renderer.
 739       listeners_.RemoveListenersForProcess(renderer);
 740       break;
 741     }
 742     case extensions::NOTIFICATION_EXTENSION_ENABLED: {
 743       // If the extension has a lazy background page, make sure it gets loaded
 744       // to register the events the extension is interested in.
 745       const Extension* extension =
 746           content::Details<const Extension>(details).ptr();
 747       if (BackgroundInfo::HasLazyBackgroundPage(extension)) {
 748         LazyBackgroundTaskQueue* queue = ExtensionSystem::Get(
 749             browser_context_)->lazy_background_task_queue();
 750         queue->AddPendingTask(browser_context_, extension->id(),
 751                               base::Bind(&DoNothing));
 752       }
 753       break;
 754     }
 755     default:
 756       NOTREACHED();
 757   }
 758 }
 759
 760 void EventRouter::OnExtensionLoaded(content::BrowserContext* browser_context,
 761                                     const Extension* extension) {
 762   // Add all registered lazy listeners to our cache.
 763   std::set<std::string> registered_events =
 764       GetRegisteredEvents(extension->id());
 765   listeners_.LoadUnfilteredLazyListeners(extension->id(), registered_events);
 766   const DictionaryValue* filtered_events = GetFilteredEvents(extension->id());
 767   if (filtered_events)
 768     listeners_.LoadFilteredLazyListeners(extension->id(), *filtered_events);
 769 }
 770
 771 void EventRouter::OnExtensionUnloaded(content::BrowserContext* browser_context,
 772                                       const Extension* extension,
 773                                       UnloadedExtensionInfo::Reason reason) {
 774   // Remove all registered listeners from our cache.
 775   listeners_.RemoveListenersForExtension(extension->id());
 776 }
 777
 778 Event::Event(const std::string& event_name,
 779              scoped_ptr<base::ListValue> event_args)
 780     : event_name(event_name),
 781       event_args(event_args.Pass()),
 782       restrict_to_browser_context(NULL),
 783       user_gesture(EventRouter::USER_GESTURE_UNKNOWN) {
 784   DCHECK(this->event_args.get());
 785 }
 786
 787 Event::Event(const std::string& event_name,
 788              scoped_ptr<base::ListValue> event_args,
 789              BrowserContext* restrict_to_browser_context)
 790     : event_name(event_name),
 791       event_args(event_args.Pass()),
 792       restrict_to_browser_context(restrict_to_browser_context),
 793       user_gesture(EventRouter::USER_GESTURE_UNKNOWN) {
 794   DCHECK(this->event_args.get());
 795 }
 796
 797 Event::Event(const std::string& event_name,
 798              scoped_ptr<ListValue> event_args,
 799              BrowserContext* restrict_to_browser_context,
 800              const GURL& event_url,
 801              EventRouter::UserGestureState user_gesture,
 802              const EventFilteringInfo& filter_info)
 803     : event_name(event_name),
 804       event_args(event_args.Pass()),
 805       restrict_to_browser_context(restrict_to_browser_context),
 806       event_url(event_url),
 807       user_gesture(user_gesture),
 808       filter_info(filter_info) {
 809   DCHECK(this->event_args.get());
 810 }
 811
 812 Event::~Event() {}
 813
 814 Event* Event::DeepCopy() {
 815   Event* copy = new Event(event_name,
 816                           scoped_ptr<base::ListValue>(event_args->DeepCopy()),
 817                           restrict_to_browser_context,
 818                           event_url,
 819                           user_gesture,
 820                           filter_info);
 821   copy->will_dispatch_callback = will_dispatch_callback;
 822   return copy;
 823 }
 824
 825 EventListenerInfo::EventListenerInfo(const std::string& event_name,
 826                                      const std::string& extension_id,
 827                                      const GURL& listener_url,
 828                                      content::BrowserContext* browser_context)
 829     : event_name(event_name),
 830       extension_id(extension_id),
 831       listener_url(listener_url),
 832       browser_context(browser_context) {
 833 }
 834
 835 }  // namespace extensions