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   if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
 159     // This is called from WebRequest API.
 160     // TODO(lazyboy): Skip this entirely: http://crbug.com/488747.
 161     BrowserThread::PostTask(
 162         BrowserThread::UI, FROM_HERE,
 163         base::Bind(&EventRouter::IncrementInFlightEventsOnUI,
 164                    browser_context_id, extension_id, event_id, event_name));
 165   } else {
 166     IncrementInFlightEventsOnUI(browser_context_id, extension_id, event_id,
 167                                 event_name);
 168   }
 169
 170   DispatchExtensionMessage(ipc_sender, browser_context_id, extension_id,
 171                            event_id, event_name, event_args.get(), user_gesture,
 172                            info);
 173 }
 174
 175 EventRouter::EventRouter(BrowserContext* browser_context,
 176                          ExtensionPrefs* extension_prefs)
 177     : browser_context_(browser_context),
 178       extension_prefs_(extension_prefs),
 179       extension_registry_observer_(this),
 180       listeners_(this) {
 181   registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_TERMINATED,
 182                  content::NotificationService::AllSources());
 183   registrar_.Add(this, content::NOTIFICATION_RENDERER_PROCESS_CLOSED,
 184                  content::NotificationService::AllSources());
 185   registrar_.Add(this,
 186                  extensions::NOTIFICATION_EXTENSION_ENABLED,
 187                  content::Source<BrowserContext>(browser_context_));
 188   extension_registry_observer_.Add(ExtensionRegistry::Get(browser_context_));
 189 }
 190
 191 EventRouter::~EventRouter() {}
 192
 193 void EventRouter::AddEventListener(const std::string& event_name,
 194                                    content::RenderProcessHost* process,
 195                                    const std::string& extension_id) {
 196   listeners_.AddListener(EventListener::ForExtension(
 197       event_name, extension_id, process, scoped_ptr<DictionaryValue>()));
 198 }
 199
 200 void EventRouter::RemoveEventListener(const std::string& event_name,
 201                                       content::RenderProcessHost* process,
 202                                       const std::string& extension_id) {
 203   scoped_ptr<EventListener> listener = EventListener::ForExtension(
 204       event_name, extension_id, process, scoped_ptr<DictionaryValue>());
 205   listeners_.RemoveListener(listener.get());
 206 }
 207
 208 void EventRouter::AddEventListenerForURL(const std::string& event_name,
 209                                          content::RenderProcessHost* process,
 210                                          const GURL& listener_url) {
 211   listeners_.AddListener(EventListener::ForURL(
 212       event_name, listener_url, process, scoped_ptr<DictionaryValue>()));
 213 }
 214
 215 void EventRouter::RemoveEventListenerForURL(const std::string& event_name,
 216                                             content::RenderProcessHost* process,
 217                                             const GURL& listener_url) {
 218   scoped_ptr<EventListener> listener = EventListener::ForURL(
 219       event_name, listener_url, process, scoped_ptr<DictionaryValue>());
 220   listeners_.RemoveListener(listener.get());
 221 }
 222
 223 void EventRouter::RegisterObserver(Observer* observer,
 224                                    const std::string& event_name) {
 225   // Observing sub-event names like "foo.onBar/123" is not allowed.
 226   DCHECK(event_name.find('/') == std::string::npos);
 227   observers_[event_name] = observer;
 228 }
 229
 230 void EventRouter::UnregisterObserver(Observer* observer) {
 231   std::vector<ObserverMap::iterator> iters_to_remove;
 232   for (ObserverMap::iterator iter = observers_.begin();
 233        iter != observers_.end(); ++iter) {
 234     if (iter->second == observer)
 235       iters_to_remove.push_back(iter);
 236   }
 237   for (size_t i = 0; i < iters_to_remove.size(); ++i)
 238     observers_.erase(iters_to_remove[i]);
 239 }
 240
 241 void EventRouter::OnListenerAdded(const EventListener* listener) {
 242   const EventListenerInfo details(listener->event_name(),
 243                                   listener->extension_id(),
 244                                   listener->listener_url(),
 245                                   listener->GetBrowserContext());
 246   std::string base_event_name = GetBaseEventName(listener->event_name());
 247   ObserverMap::iterator observer = observers_.find(base_event_name);
 248   if (observer != observers_.end())
 249     observer->second->OnListenerAdded(details);
 250 }
 251
 252 void EventRouter::OnListenerRemoved(const EventListener* listener) {
 253   const EventListenerInfo details(listener->event_name(),
 254                                   listener->extension_id(),
 255                                   listener->listener_url(),
 256                                   listener->GetBrowserContext());
 257   std::string base_event_name = GetBaseEventName(listener->event_name());
 258   ObserverMap::iterator observer = observers_.find(base_event_name);
 259   if (observer != observers_.end())
 260     observer->second->OnListenerRemoved(details);
 261 }
 262
 263 void EventRouter::AddLazyEventListener(const std::string& event_name,
 264                                        const std::string& extension_id) {
 265   bool is_new = listeners_.AddListener(EventListener::ForExtension(
 266       event_name, extension_id, NULL, scoped_ptr<DictionaryValue>()));
 267
 268   if (is_new) {
 269     std::set<std::string> events = GetRegisteredEvents(extension_id);
 270     bool prefs_is_new = events.insert(event_name).second;
 271     if (prefs_is_new)
 272       SetRegisteredEvents(extension_id, events);
 273   }
 274 }
 275
 276 void EventRouter::RemoveLazyEventListener(const std::string& event_name,
 277                                           const std::string& extension_id) {
 278   scoped_ptr<EventListener> listener = EventListener::ForExtension(
 279       event_name, extension_id, NULL, scoped_ptr<DictionaryValue>());
 280   bool did_exist = listeners_.RemoveListener(listener.get());
 281
 282   if (did_exist) {
 283     std::set<std::string> events = GetRegisteredEvents(extension_id);
 284     bool prefs_did_exist = events.erase(event_name) > 0;
 285     DCHECK(prefs_did_exist);
 286     SetRegisteredEvents(extension_id, events);
 287   }
 288 }
 289
 290 void EventRouter::AddFilteredEventListener(const std::string& event_name,
 291                                            content::RenderProcessHost* process,
 292                                            const std::string& extension_id,
 293                                            const base::DictionaryValue& filter,
 294                                            bool add_lazy_listener) {
 295   listeners_.AddListener(EventListener::ForExtension(
 296       event_name,
 297       extension_id,
 298       process,
 299       scoped_ptr<DictionaryValue>(filter.DeepCopy())));
 300
 301   if (add_lazy_listener) {
 302     bool added = listeners_.AddListener(EventListener::ForExtension(
 303         event_name,
 304         extension_id,
 305         NULL,
 306         scoped_ptr<DictionaryValue>(filter.DeepCopy())));
 307
 308     if (added)
 309       AddFilterToEvent(event_name, extension_id, &filter);
 310   }
 311 }
 312
 313 void EventRouter::RemoveFilteredEventListener(
 314     const std::string& event_name,
 315     content::RenderProcessHost* process,
 316     const std::string& extension_id,
 317     const base::DictionaryValue& filter,
 318     bool remove_lazy_listener) {
 319   scoped_ptr<EventListener> listener = EventListener::ForExtension(
 320       event_name,
 321       extension_id,
 322       process,
 323       scoped_ptr<DictionaryValue>(filter.DeepCopy()));
 324
 325   listeners_.RemoveListener(listener.get());
 326
 327   if (remove_lazy_listener) {
 328     listener->MakeLazy();
 329     bool removed = listeners_.RemoveListener(listener.get());
 330
 331     if (removed)
 332       RemoveFilterFromEvent(event_name, extension_id, &filter);
 333   }
 334 }
 335
 336 bool EventRouter::HasEventListener(const std::string& event_name) {
 337   return listeners_.HasListenerForEvent(event_name);
 338 }
 339
 340 bool EventRouter::ExtensionHasEventListener(const std::string& extension_id,
 341                                             const std::string& event_name) {
 342   return listeners_.HasListenerForExtension(extension_id, event_name);
 343 }
 344
 345 bool EventRouter::HasEventListenerImpl(const ListenerMap& listener_map,
 346                                        const std::string& extension_id,
 347                                        const std::string& event_name) {
 348   ListenerMap::const_iterator it = listener_map.find(event_name);
 349   if (it == listener_map.end())
 350     return false;
 351
 352   const std::set<ListenerProcess>& listeners = it->second;
 353   if (extension_id.empty())
 354     return !listeners.empty();
 355
 356   for (std::set<ListenerProcess>::const_iterator listener = listeners.begin();
 357        listener != listeners.end(); ++listener) {
 358     if (listener->extension_id == extension_id)
 359       return true;
 360   }
 361   return false;
 362 }
 363
 364 std::set<std::string> EventRouter::GetRegisteredEvents(
 365     const std::string& extension_id) {
 366   std::set<std::string> events;
 367   const ListValue* events_value = NULL;
 368
 369   if (!extension_prefs_ ||
 370       !extension_prefs_->ReadPrefAsList(
 371            extension_id, kRegisteredEvents, &events_value)) {
 372     return events;
 373   }
 374
 375   for (size_t i = 0; i < events_value->GetSize(); ++i) {
 376     std::string event;
 377     if (events_value->GetString(i, &event))
 378       events.insert(event);
 379   }
 380   return events;
 381 }
 382
 383 void EventRouter::SetRegisteredEvents(const std::string& extension_id,
 384                                       const std::set<std::string>& events) {
 385   ListValue* events_value = new ListValue;
 386   for (std::set<std::string>::const_iterator iter = events.begin();
 387        iter != events.end(); ++iter) {
 388     events_value->Append(new base::StringValue(*iter));
 389   }
 390   extension_prefs_->UpdateExtensionPref(
 391       extension_id, kRegisteredEvents, events_value);
 392 }
 393
 394 void EventRouter::AddFilterToEvent(const std::string& event_name,
 395                                    const std::string& extension_id,
 396                                    const DictionaryValue* filter) {
 397   ExtensionPrefs::ScopedDictionaryUpdate update(
 398       extension_prefs_, extension_id, kFilteredEvents);
 399   DictionaryValue* filtered_events = update.Get();
 400   if (!filtered_events)
 401     filtered_events = update.Create();
 402
 403   ListValue* filter_list = NULL;
 404   if (!filtered_events->GetList(event_name, &filter_list)) {
 405     filter_list = new ListValue;
 406     filtered_events->SetWithoutPathExpansion(event_name, filter_list);
 407   }
 408
 409   filter_list->Append(filter->DeepCopy());
 410 }
 411
 412 void EventRouter::RemoveFilterFromEvent(const std::string& event_name,
 413                                         const std::string& extension_id,
 414                                         const DictionaryValue* filter) {
 415   ExtensionPrefs::ScopedDictionaryUpdate update(
 416       extension_prefs_, extension_id, kFilteredEvents);
 417   DictionaryValue* filtered_events = update.Get();
 418   ListValue* filter_list = NULL;
 419   if (!filtered_events ||
 420       !filtered_events->GetListWithoutPathExpansion(event_name, &filter_list)) {
 421     return;
 422   }
 423
 424   for (size_t i = 0; i < filter_list->GetSize(); i++) {
 425     DictionaryValue* filter = NULL;
 426     CHECK(filter_list->GetDictionary(i, &filter));
 427     if (filter->Equals(filter)) {
 428       filter_list->Remove(i, NULL);
 429       break;
 430     }
 431   }
 432 }
 433
 434 const DictionaryValue* EventRouter::GetFilteredEvents(
 435     const std::string& extension_id) {
 436   const DictionaryValue* events = NULL;
 437   extension_prefs_->ReadPrefAsDictionary(
 438       extension_id, kFilteredEvents, &events);
 439   return events;
 440 }
 441
 442 void EventRouter::BroadcastEvent(scoped_ptr<Event> event) {
 443   DispatchEventImpl(std::string(), linked_ptr<Event>(event.release()));
 444 }
 445
 446 void EventRouter::DispatchEventToExtension(const std::string& extension_id,
 447                                            scoped_ptr<Event> event) {
 448   DCHECK(!extension_id.empty());
 449   DispatchEventImpl(extension_id, linked_ptr<Event>(event.release()));
 450 }
 451
 452 void EventRouter::DispatchEventWithLazyListener(const std::string& extension_id,
 453                                                 scoped_ptr<Event> event) {
 454   DCHECK(!extension_id.empty());
 455   std::string event_name = event->event_name;
 456   bool has_listener = ExtensionHasEventListener(extension_id, event_name);
 457   if (!has_listener)
 458     AddLazyEventListener(event_name, extension_id);
 459   DispatchEventToExtension(extension_id, event.Pass());
 460   if (!has_listener)
 461     RemoveLazyEventListener(event_name, extension_id);
 462 }
 463
 464 void EventRouter::DispatchEventImpl(const std::string& restrict_to_extension_id,
 465                                     const linked_ptr<Event>& event) {
 466   // We don't expect to get events from a completely different browser context.
 467   DCHECK(!event->restrict_to_browser_context ||
 468          ExtensionsBrowserClient::Get()->IsSameContext(
 469              browser_context_, event->restrict_to_browser_context));
 470
 471   std::set<const EventListener*> listeners(
 472       listeners_.GetEventListeners(*event));
 473
 474   std::set<EventDispatchIdentifier> already_dispatched;
 475
 476   // We dispatch events for lazy background pages first because attempting to do
 477   // so will cause those that are being suspended to cancel that suspension.
 478   // As canceling a suspension entails sending an event to the affected
 479   // background page, and as that event needs to be delivered before we dispatch
 480   // the event we are dispatching here, we dispatch to the lazy listeners here
 481   // first.
 482   for (std::set<const EventListener*>::iterator it = listeners.begin();
 483        it != listeners.end(); it++) {
 484     const EventListener* listener = *it;
 485     if (restrict_to_extension_id.empty() ||
 486         restrict_to_extension_id == listener->extension_id()) {
 487       if (listener->IsLazy()) {
 488         DispatchLazyEvent(listener->extension_id(), event, &already_dispatched);
 489       }
 490     }
 491   }
 492
 493   for (std::set<const EventListener*>::iterator it = listeners.begin();
 494        it != listeners.end(); it++) {
 495     const EventListener* listener = *it;
 496     if (restrict_to_extension_id.empty() ||
 497         restrict_to_extension_id == listener->extension_id()) {
 498       if (listener->process()) {
 499         EventDispatchIdentifier dispatch_id(listener->GetBrowserContext(),
 500                                             listener->extension_id());
 501         if (!ContainsKey(already_dispatched, dispatch_id)) {
 502           DispatchEventToProcess(listener->extension_id(),
 503                                  listener->listener_url(),
 504                                  listener->process(),
 505                                  event);
 506         }
 507       }
 508     }
 509   }
 510 }
 511
 512 void EventRouter::DispatchLazyEvent(
 513     const std::string& extension_id,
 514     const linked_ptr<Event>& event,
 515     std::set<EventDispatchIdentifier>* already_dispatched) {
 516   // Check both the original and the incognito browser context to see if we
 517   // should load a lazy bg page to handle the event. The latter case
 518   // occurs in the case of split-mode extensions.
 519   const Extension* extension =
 520       ExtensionRegistry::Get(browser_context_)->enabled_extensions().GetByID(
 521           extension_id);
 522   if (!extension)
 523     return;
 524
 525   if (MaybeLoadLazyBackgroundPageToDispatchEvent(
 526           browser_context_, extension, event)) {
 527     already_dispatched->insert(std::make_pair(browser_context_, extension_id));
 528   }
 529
 530   ExtensionsBrowserClient* browser_client = ExtensionsBrowserClient::Get();
 531   if (browser_client->HasOffTheRecordContext(browser_context_) &&
 532       IncognitoInfo::IsSplitMode(extension)) {
 533     BrowserContext* incognito_context =
 534         browser_client->GetOffTheRecordContext(browser_context_);
 535     if (MaybeLoadLazyBackgroundPageToDispatchEvent(
 536             incognito_context, extension, event)) {
 537       already_dispatched->insert(
 538           std::make_pair(incognito_context, extension_id));
 539     }
 540   }
 541 }
 542
 543 void EventRouter::DispatchEventToProcess(const std::string& extension_id,
 544                                          const GURL& listener_url,
 545                                          content::RenderProcessHost* process,
 546                                          const linked_ptr<Event>& event) {
 547   BrowserContext* listener_context = process->GetBrowserContext();
 548   ProcessMap* process_map = ProcessMap::Get(listener_context);
 549
 550   // NOTE: |extension| being NULL does not necessarily imply that this event
 551   // shouldn't be dispatched. Events can be dispatched to WebUI and webviews as
 552   // well.  It all depends on what GetMostLikelyContextType returns.
 553   const Extension* extension =
 554       ExtensionRegistry::Get(browser_context_)->enabled_extensions().GetByID(
 555           extension_id);
 556
 557   if (!extension && !extension_id.empty()) {
 558     // Trying to dispatch an event to an extension that doesn't exist. The
 559     // extension could have been removed, but we do not unregister it until the
 560     // extension process is unloaded.
 561     return;
 562   }
 563
 564   if (extension) {
 565     // Extension-specific checks.
 566     // Firstly, if the event is for a URL, the Extension must have permission
 567     // to access that URL.
 568     if (!event->event_url.is_empty() &&
 569         event->event_url.host() != extension->id() &&  // event for self is ok
 570         !extension->permissions_data()
 571              ->active_permissions()
 572              ->HasEffectiveAccessToURL(event->event_url)) {
 573       return;
 574     }
 575     // Secondly, if the event is for incognito mode, the Extension must be
 576     // enabled in incognito mode.
 577     if (!CanDispatchEventToBrowserContext(listener_context, extension, event)) {
 578       return;
 579     }
 580   }
 581
 582   Feature::Context target_context =
 583       process_map->GetMostLikelyContextType(extension, process->GetID());
 584
 585   // We shouldn't be dispatching an event to a webpage, since all such events
 586   // (e.g.  messaging) don't go through EventRouter.
 587   DCHECK_NE(Feature::WEB_PAGE_CONTEXT, target_context)
 588       << "Trying to dispatch event " << event->event_name << " to a webpage,"
 589       << " but this shouldn't be possible";
 590
 591   Feature::Availability availability =
 592       ExtensionAPI::GetSharedInstance()->IsAvailable(
 593           event->event_name, extension, target_context, listener_url);
 594   if (!availability.is_available()) {
 595     // It shouldn't be possible to reach here, because access is checked on
 596     // registration. However, for paranoia, check on dispatch as well.
 597     NOTREACHED() << "Trying to dispatch event " << event->event_name
 598                  << " which the target does not have access to: "
 599                  << availability.message();
 600     return;
 601   }
 602
 603   if (!event->will_dispatch_callback.is_null() &&
 604       !event->will_dispatch_callback.Run(listener_context, extension,
 605                                          event->event_args.get())) {
 606     return;
 607   }
 608
 609   int event_id = g_extension_event_id.GetNext();
 610   DispatchExtensionMessage(process, listener_context, extension_id, event_id,
 611                            event->event_name, event->event_args.get(),
 612                            event->user_gesture, event->filter_info);
 613
 614   if (extension) {
 615     IncrementInFlightEvents(listener_context, extension, event_id,
 616                             event->event_name);
 617   }
 618 }
 619
 620 bool EventRouter::CanDispatchEventToBrowserContext(
 621     BrowserContext* context,
 622     const Extension* extension,
 623     const linked_ptr<Event>& event) {
 624   // Is this event from a different browser context than the renderer (ie, an
 625   // incognito tab event sent to a normal process, or vice versa).
 626   bool cross_incognito = event->restrict_to_browser_context &&
 627                          context != event->restrict_to_browser_context;
 628   if (!cross_incognito)
 629     return true;
 630   return ExtensionsBrowserClient::Get()->CanExtensionCrossIncognito(
 631       extension, context);
 632 }
 633
 634 bool EventRouter::MaybeLoadLazyBackgroundPageToDispatchEvent(
 635     BrowserContext* context,
 636     const Extension* extension,
 637     const linked_ptr<Event>& event) {
 638   if (!CanDispatchEventToBrowserContext(context, extension, event))
 639     return false;
 640
 641   LazyBackgroundTaskQueue* queue = ExtensionSystem::Get(
 642       context)->lazy_background_task_queue();
 643   if (queue->ShouldEnqueueTask(context, extension)) {
 644     linked_ptr<Event> dispatched_event(event);
 645
 646     // If there's a dispatch callback, call it now (rather than dispatch time)
 647     // to avoid lifetime issues. Use a separate copy of the event args, so they
 648     // last until the event is dispatched.
 649     if (!event->will_dispatch_callback.is_null()) {
 650       dispatched_event.reset(event->DeepCopy());
 651       if (!dispatched_event->will_dispatch_callback.Run(
 652               context, extension, dispatched_event->event_args.get())) {
 653         // The event has been canceled.
 654         return true;
 655       }
 656       // Ensure we don't call it again at dispatch time.
 657       dispatched_event->will_dispatch_callback.Reset();
 658     }
 659
 660     queue->AddPendingTask(context, extension->id(),
 661                           base::Bind(&EventRouter::DispatchPendingEvent,
 662                                      base::Unretained(this), dispatched_event));
 663     return true;
 664   }
 665
 666   return false;
 667 }
 668
 669 // static
 670 void EventRouter::IncrementInFlightEventsOnUI(void* browser_context_id,
 671                                               const std::string& extension_id,
 672                                               int event_id,
 673                                               const std::string& event_name) {
 674   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 675   BrowserContext* browser_context =
 676       reinterpret_cast<BrowserContext*>(browser_context_id);
 677   if (!ExtensionsBrowserClient::Get()->IsValidContext(browser_context))
 678     return;
 679   EventRouter* event_router = EventRouter::Get(browser_context);
 680   if (!event_router)
 681     return;
 682   const Extension* extension =
 683       ExtensionRegistry::Get(browser_context)->enabled_extensions().GetByID(
 684           extension_id);
 685   if (!extension)
 686     return;
 687   event_router->IncrementInFlightEvents(browser_context, extension, event_id,
 688                                         event_name);
 689 }
 690
 691 void EventRouter::IncrementInFlightEvents(BrowserContext* context,
 692                                           const Extension* extension,
 693                                           int event_id,
 694                                           const std::string& event_name) {
 695   // TODO(chirantan): Turn this on once crbug.com/464513 is fixed.
 696   // DCHECK_CURRENTLY_ON(BrowserThread::UI);
 697
 698   // Only increment in-flight events if the lazy background page is active,
 699   // because that's the only time we'll get an ACK.
 700   if (BackgroundInfo::HasLazyBackgroundPage(extension)) {
 701     ProcessManager* pm = ProcessManager::Get(context);
 702     ExtensionHost* host = pm->GetBackgroundHostForExtension(extension->id());
 703     if (host) {
 704       pm->IncrementLazyKeepaliveCount(extension);
 705       host->OnBackgroundEventDispatched(event_name, event_id);
 706     }
 707   }
 708 }
 709
 710 void EventRouter::OnEventAck(BrowserContext* context,
 711                              const std::string& extension_id) {
 712   ProcessManager* pm = ProcessManager::Get(context);
 713   ExtensionHost* host = pm->GetBackgroundHostForExtension(extension_id);
 714   // The event ACK is routed to the background host, so this should never be
 715   // NULL.
 716   CHECK(host);
 717   // TODO(mpcomplete): We should never get this message unless
 718   // HasLazyBackgroundPage is true. Find out why we're getting it anyway.
 719   if (host->extension() &&
 720       BackgroundInfo::HasLazyBackgroundPage(host->extension()))
 721     pm->DecrementLazyKeepaliveCount(host->extension());
 722 }
 723
 724 void EventRouter::DispatchPendingEvent(const linked_ptr<Event>& event,
 725                                        ExtensionHost* host) {
 726   if (!host)
 727     return;
 728
 729   if (listeners_.HasProcessListener(host->render_process_host(),
 730                                     host->extension()->id())) {
 731     // URL events cannot be lazy therefore can't be pending, hence the GURL().
 732     DispatchEventToProcess(
 733         host->extension()->id(), GURL(), host->render_process_host(), event);
 734   }
 735 }
 736
 737 void EventRouter::Observe(int type,
 738                           const content::NotificationSource& source,
 739                           const content::NotificationDetails& details) {
 740   switch (type) {
 741     case content::NOTIFICATION_RENDERER_PROCESS_TERMINATED:
 742     case content::NOTIFICATION_RENDERER_PROCESS_CLOSED: {
 743       content::RenderProcessHost* renderer =
 744           content::Source<content::RenderProcessHost>(source).ptr();
 745       // Remove all event listeners associated with this renderer.
 746       listeners_.RemoveListenersForProcess(renderer);
 747       break;
 748     }
 749     case extensions::NOTIFICATION_EXTENSION_ENABLED: {
 750       // If the extension has a lazy background page, make sure it gets loaded
 751       // to register the events the extension is interested in.
 752       const Extension* extension =
 753           content::Details<const Extension>(details).ptr();
 754       if (BackgroundInfo::HasLazyBackgroundPage(extension)) {
 755         LazyBackgroundTaskQueue* queue = ExtensionSystem::Get(
 756             browser_context_)->lazy_background_task_queue();
 757         queue->AddPendingTask(browser_context_, extension->id(),
 758                               base::Bind(&DoNothing));
 759       }
 760       break;
 761     }
 762     default:
 763       NOTREACHED();
 764   }
 765 }
 766
 767 void EventRouter::OnExtensionLoaded(content::BrowserContext* browser_context,
 768                                     const Extension* extension) {
 769   // Add all registered lazy listeners to our cache.
 770   std::set<std::string> registered_events =
 771       GetRegisteredEvents(extension->id());
 772   listeners_.LoadUnfilteredLazyListeners(extension->id(), registered_events);
 773   const DictionaryValue* filtered_events = GetFilteredEvents(extension->id());
 774   if (filtered_events)
 775     listeners_.LoadFilteredLazyListeners(extension->id(), *filtered_events);
 776 }
 777
 778 void EventRouter::OnExtensionUnloaded(content::BrowserContext* browser_context,
 779                                       const Extension* extension,
 780                                       UnloadedExtensionInfo::Reason reason) {
 781   // Remove all registered listeners from our cache.
 782   listeners_.RemoveListenersForExtension(extension->id());
 783 }
 784
 785 Event::Event(const std::string& event_name,
 786              scoped_ptr<base::ListValue> event_args)
 787     : event_name(event_name),
 788       event_args(event_args.Pass()),
 789       restrict_to_browser_context(NULL),
 790       user_gesture(EventRouter::USER_GESTURE_UNKNOWN) {
 791   DCHECK(this->event_args.get());
 792 }
 793
 794 Event::Event(const std::string& event_name,
 795              scoped_ptr<base::ListValue> event_args,
 796              BrowserContext* restrict_to_browser_context)
 797     : event_name(event_name),
 798       event_args(event_args.Pass()),
 799       restrict_to_browser_context(restrict_to_browser_context),
 800       user_gesture(EventRouter::USER_GESTURE_UNKNOWN) {
 801   DCHECK(this->event_args.get());
 802 }
 803
 804 Event::Event(const std::string& event_name,
 805              scoped_ptr<ListValue> event_args,
 806              BrowserContext* restrict_to_browser_context,
 807              const GURL& event_url,
 808              EventRouter::UserGestureState user_gesture,
 809              const EventFilteringInfo& filter_info)
 810     : event_name(event_name),
 811       event_args(event_args.Pass()),
 812       restrict_to_browser_context(restrict_to_browser_context),
 813       event_url(event_url),
 814       user_gesture(user_gesture),
 815       filter_info(filter_info) {
 816   DCHECK(this->event_args.get());
 817 }
 818
 819 Event::~Event() {}
 820
 821 Event* Event::DeepCopy() {
 822   Event* copy = new Event(event_name,
 823                           scoped_ptr<base::ListValue>(event_args->DeepCopy()),
 824                           restrict_to_browser_context,
 825                           event_url,
 826                           user_gesture,
 827                           filter_info);
 828   copy->will_dispatch_callback = will_dispatch_callback;
 829   return copy;
 830 }
 831
 832 EventListenerInfo::EventListenerInfo(const std::string& event_name,
 833                                      const std::string& extension_id,
 834                                      const GURL& listener_url,
 835                                      content::BrowserContext* browser_context)
 836     : event_name(event_name),
 837       extension_id(extension_id),
 838       listener_url(listener_url),
 839       browser_context(browser_context) {
 840 }
 841
 842 }  // namespace extensions