BackgroundSyncManager tracks client registrations

content/browser/background_sync/background_sync_manager.cc

Index: content/browser/background_sync/background_sync_manager.cc
diff --git a/content/browser/background_sync/background_sync_manager.cc b/content/browser/background_sync/background_sync_manager.cc
index 018bbae5ab270ecfc3905a191a9fbb48dd63cb93..976effd4c85fe5d93dc063267dcf5acf9c9007b9 100644
--- a/content/browser/background_sync/background_sync_manager.cc
+++ b/content/browser/background_sync/background_sync_manager.cc
@@ -12,6 +12,7 @@
 #include "content/browser/background_sync/background_sync_metrics.h"
 #include "content/browser/background_sync/background_sync_network_observer.h"
 #include "content/browser/background_sync/background_sync_power_observer.h"
+#include "content/browser/background_sync/background_sync_registration_handle.h"
 #include "content/browser/background_sync/background_sync_registration_options.h"
 #include "content/browser/service_worker/service_worker_context_wrapper.h"
 #include "content/browser/service_worker/service_worker_storage.h"
@@ -21,11 +22,36 @@
 #include "content/browser/android/background_sync_launcher_android.h"
 #endif
 
+namespace content {
+
+class BackgroundSyncManager::RefCountedRegistration
+    : public base::RefCounted<RefCountedRegistration> {
+ public:
+  BackgroundSyncRegistration* value() { return &registration_; }
+  const BackgroundSyncRegistration* value() const { return &registration_; }
+
+ private:
+  friend class base::RefCounted<RefCountedRegistration>;
+  virtual ~RefCountedRegistration() = default;

[michaeln, 2015/08/28 02:53:11]

does this need to be virtual? if not, nix the vtable

[jkarlin, 2015/09/02 23:51:40]

Done.

+
+  BackgroundSyncRegistration registration_;
+};
+
 namespace {
+
 const char kBackgroundSyncUserDataKey[] = "BackgroundSyncUserData";
+
+void PostErrorResponse(
+    BackgroundSyncStatus status,
+    const BackgroundSyncManager::StatusAndRegistrationCallback& callback) {
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE,
+      base::Bind(
+          callback, status,
+          base::Passed(scoped_ptr<BackgroundSyncRegistrationHandle>().Pass())));
 }
 
-namespace content {
+}  // namespace
 
 BackgroundSyncManager::BackgroundSyncRegistrations::
     BackgroundSyncRegistrations()
@@ -87,9 +113,7 @@ void BackgroundSyncManager::Register(
         options.periodicity, registration_could_fire,
         BackgroundSyncMetrics::REGISTRATION_IS_NOT_DUPLICATE,
         BACKGROUND_SYNC_STATUS_STORAGE_ERROR);
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR,
-                              BackgroundSyncRegistration()));
+    PostErrorResponse(BACKGROUND_SYNC_STATUS_STORAGE_ERROR, callback);
     return;
   }
 
@@ -99,30 +123,6 @@ void BackgroundSyncManager::Register(
                  MakeStatusAndRegistrationCompletion(callback)));
 }
 
-void BackgroundSyncManager::Unregister(
-    int64 sw_registration_id,
-    const std::string& sync_registration_tag,
-    SyncPeriodicity periodicity,
-    BackgroundSyncRegistration::RegistrationId sync_registration_id,
-    const StatusCallback& callback) {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
-
-  if (disabled_) {
-    BackgroundSyncMetrics::CountUnregister(
-        periodicity, BACKGROUND_SYNC_STATUS_STORAGE_ERROR);
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR));
-    return;
-  }
-
-  RegistrationKey registration_key(sync_registration_tag, periodicity);
-
-  op_scheduler_.ScheduleOperation(base::Bind(
-      &BackgroundSyncManager::UnregisterImpl, weak_ptr_factory_.GetWeakPtr(),
-      sw_registration_id, registration_key, sync_registration_id, periodicity,
-      MakeStatusCompletion(callback)));
-}
-
 void BackgroundSyncManager::GetRegistration(
     int64 sw_registration_id,
     const std::string& sync_registration_tag,
@@ -131,9 +131,7 @@ void BackgroundSyncManager::GetRegistration(
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   if (disabled_) {
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR,
-                              BackgroundSyncRegistration()));
+    PostErrorResponse(BACKGROUND_SYNC_STATUS_STORAGE_ERROR, callback);
     return;
   }
 
@@ -153,8 +151,12 @@ void BackgroundSyncManager::GetRegistrations(
 
   if (disabled_) {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR,
-                              std::vector<BackgroundSyncRegistration>()));
+        FROM_HERE,
+        base::Bind(
+            callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR,
+            base::Passed(
+                scoped_ptr<ScopedVector<BackgroundSyncRegistrationHandle>>()
+                    .Pass())));
     return;
   }
 
@@ -164,6 +166,21 @@ void BackgroundSyncManager::GetRegistrations(
                  periodicity, MakeStatusAndRegistrationsCompletion(callback)));
 }
 
+// Given a HandleId |handle_id|, return a new handle for the same
+// registration.
+scoped_ptr<BackgroundSyncRegistrationHandle>
+BackgroundSyncManager::DuplicateRegistrationHandle(
+    int64 sw_registration_id,

[michaeln, 2015/08/28 02:53:11]

|sw_registration_id| is not used, nix it?

[jkarlin, 2015/09/02 23:51:40]

Done.

+    BackgroundSyncRegistrationHandle::HandleId handle_id) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  scoped_refptr<RefCountedRegistration>* ref_registration =
+      registration_handle_ids_.Lookup(handle_id);
+  if (!ref_registration)
+    return scoped_ptr<BackgroundSyncRegistrationHandle>();
+  return CreateRegistrationHandle(ref_registration->get());
+}
+
 void BackgroundSyncManager::OnRegistrationDeleted(int64 registration_id,
                                                   const GURL& pattern) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
@@ -245,7 +262,7 @@ void BackgroundSyncManager::InitDidGetDataFromBackend(
     BackgroundSyncRegistrationsProto registrations_proto;
     if (registrations_proto.ParseFromString(data.second)) {
       BackgroundSyncRegistrations* registrations =
-          &sw_to_registrations_map_[data.first];
+          &active_registrations_[data.first];
       registrations->next_id = registrations_proto.next_registration_id();
       registrations->origin = GURL(registrations_proto.origin());
 
@@ -261,8 +278,11 @@ void BackgroundSyncManager::InitDidGetDataFromBackend(
 
         RegistrationKey registration_key(registration_proto.tag(),
                                          registration_proto.periodicity());
-        BackgroundSyncRegistration* registration =
-            &registrations->registration_map[registration_key];
+
+        scoped_refptr<RefCountedRegistration> ref_registration(
+            new RefCountedRegistration());
+        registrations->registration_map[registration_key] = ref_registration;
+        BackgroundSyncRegistration* registration = ref_registration->value();
 
         BackgroundSyncRegistrationOptions* options = registration->options();
         options->tag = registration_proto.tag();
@@ -315,9 +335,7 @@ void BackgroundSyncManager::RegisterImpl(
         options.periodicity, registration_could_fire,
         BackgroundSyncMetrics::REGISTRATION_IS_NOT_DUPLICATE,
         BACKGROUND_SYNC_STATUS_STORAGE_ERROR);
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR,
-                              BackgroundSyncRegistration()));
+    PostErrorResponse(BACKGROUND_SYNC_STATUS_STORAGE_ERROR, callback);
     return;
   }
 
@@ -328,31 +346,28 @@ void BackgroundSyncManager::RegisterImpl(
         options.periodicity, registration_could_fire,
         BackgroundSyncMetrics::REGISTRATION_IS_NOT_DUPLICATE,
         BACKGROUND_SYNC_STATUS_NO_SERVICE_WORKER);
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE,
-        base::Bind(callback, BACKGROUND_SYNC_STATUS_NO_SERVICE_WORKER,
-                   BackgroundSyncRegistration()));
+    PostErrorResponse(BACKGROUND_SYNC_STATUS_NO_SERVICE_WORKER, callback);
     return;
   }
 
   if (!sw_registration->active_version()->HasWindowClients()) {
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_NOT_ALLOWED,
-                              BackgroundSyncRegistration()));
+    PostErrorResponse(BACKGROUND_SYNC_STATUS_NOT_ALLOWED, callback);
     return;
   }
 
-  BackgroundSyncRegistration* existing_registration =
-      LookupRegistration(sw_registration_id, RegistrationKey(options));
-  if (existing_registration &&
-      existing_registration->options()->Equals(options)) {
+  RefCountedRegistration* existing_registration_ref =
+      LookupActiveRegistration(sw_registration_id, RegistrationKey(options));
+  if (existing_registration_ref &&
+      existing_registration_ref->value()->options()->Equals(options)) {
+    BackgroundSyncRegistration* existing_registration =
+        existing_registration_ref->value();
     if (existing_registration->sync_state() == SYNC_STATE_FAILED) {
       existing_registration->set_sync_state(SYNC_STATE_PENDING);
       StoreRegistrations(
           sw_registration_id,
           base::Bind(&BackgroundSyncManager::RegisterDidStore,
                      weak_ptr_factory_.GetWeakPtr(), sw_registration_id,
-                     *existing_registration, callback));
+                     make_scoped_refptr(existing_registration_ref), callback));
       return;
     }
 
@@ -363,27 +378,33 @@ void BackgroundSyncManager::RegisterImpl(
         BACKGROUND_SYNC_STATUS_OK);
 
     base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_OK,
-                              *existing_registration));
+        FROM_HERE,
+        base::Bind(
+            callback, BACKGROUND_SYNC_STATUS_OK,
+            base::Passed(
+                CreateRegistrationHandle(existing_registration_ref).Pass())));
     return;
   }
 
-  BackgroundSyncRegistration new_registration;
-  *new_registration.options() = options;
+  scoped_refptr<RefCountedRegistration> new_ref_registration(
+      new RefCountedRegistration());
+  BackgroundSyncRegistration* new_registration = new_ref_registration->value();
+
+  *new_registration->options() = options;
 
   BackgroundSyncRegistrations* registrations =
-      &sw_to_registrations_map_[sw_registration_id];
-  new_registration.set_id(registrations->next_id++);
+      &active_registrations_[sw_registration_id];
+  new_registration->set_id(registrations->next_id++);
 
-  AddRegistrationToMap(sw_registration_id,
-                       sw_registration->pattern().GetOrigin(),
-                       new_registration);
+  AddActiveRegistration(sw_registration_id,
+                        sw_registration->pattern().GetOrigin(),
+                        new_ref_registration);
 
   StoreRegistrations(
       sw_registration_id,
       base::Bind(&BackgroundSyncManager::RegisterDidStore,
                  weak_ptr_factory_.GetWeakPtr(), sw_registration_id,
-                 new_registration, callback));
+                 new_ref_registration, callback));
 }
 
 void BackgroundSyncManager::DisableAndClearManager(
@@ -397,7 +418,7 @@ void BackgroundSyncManager::DisableAndClearManager(
   }
 
   disabled_ = true;
-  sw_to_registrations_map_.clear();
+  active_registrations_.clear();
 
   // Delete all backend entries. The memory representation of registered syncs
   // may be out of sync with storage (e.g., due to corruption detection on
@@ -441,14 +462,15 @@ void BackgroundSyncManager::DisableAndClearManagerClearedOne(
                                                 base::Bind(barrier_closure));
 }
 
-BackgroundSyncRegistration* BackgroundSyncManager::LookupRegistration(
+BackgroundSyncManager::RefCountedRegistration*
+BackgroundSyncManager::LookupActiveRegistration(
     int64 sw_registration_id,
     const RegistrationKey& registration_key) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   SWIdToRegistrationsMap::iterator it =
-      sw_to_registrations_map_.find(sw_registration_id);
-  if (it == sw_to_registrations_map_.end())
+      active_registrations_.find(sw_registration_id);
+  if (it == active_registrations_.end())
     return nullptr;
 
   BackgroundSyncRegistrations& registrations = it->second;
@@ -460,7 +482,7 @@ BackgroundSyncRegistration* BackgroundSyncManager::LookupRegistration(
   if (key_and_registration_iter == registrations.registration_map.end())
     return nullptr;
 
-  return &key_and_registration_iter->second;
+  return key_and_registration_iter->second.get();
 }
 
 void BackgroundSyncManager::StoreRegistrations(
@@ -470,14 +492,14 @@ void BackgroundSyncManager::StoreRegistrations(
 
   // Serialize the data.
   const BackgroundSyncRegistrations& registrations =
-      sw_to_registrations_map_[sw_registration_id];
+      active_registrations_[sw_registration_id];
   BackgroundSyncRegistrationsProto registrations_proto;
   registrations_proto.set_next_registration_id(registrations.next_id);
   registrations_proto.set_origin(registrations.origin.spec());
 
   for (const auto& key_and_registration : registrations.registration_map) {
     const BackgroundSyncRegistration& registration =
-        key_and_registration.second;
+        *key_and_registration.second->value();
     BackgroundSyncRegistrationProto* registration_proto =
         registrations_proto.add_registration();
     registration_proto->set_id(registration.id());
@@ -499,27 +521,28 @@ void BackgroundSyncManager::StoreRegistrations(
 
 void BackgroundSyncManager::RegisterDidStore(
     int64 sw_registration_id,
-    const BackgroundSyncRegistration& new_registration,
+    const scoped_refptr<RefCountedRegistration>& new_registration_ref,
     const StatusAndRegistrationCallback& callback,
     ServiceWorkerStatusCode status) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
+  const BackgroundSyncRegistration* new_registration =
+      new_registration_ref->value();
+
   // For UMA, determine here whether the sync could fire immediately
   BackgroundSyncMetrics::RegistrationCouldFire registration_could_fire =
-      AreOptionConditionsMet(*new_registration.options())
+      AreOptionConditionsMet(*new_registration->options())
           ? BackgroundSyncMetrics::REGISTRATION_COULD_FIRE
           : BackgroundSyncMetrics::REGISTRATION_COULD_NOT_FIRE;
 
   if (status == SERVICE_WORKER_ERROR_NOT_FOUND) {
     // The service worker registration is gone.
     BackgroundSyncMetrics::CountRegister(
-        new_registration.options()->periodicity, registration_could_fire,
+        new_registration->options()->periodicity, registration_could_fire,
         BackgroundSyncMetrics::REGISTRATION_IS_NOT_DUPLICATE,
         BACKGROUND_SYNC_STATUS_STORAGE_ERROR);
-    sw_to_registrations_map_.erase(sw_registration_id);
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR,
-                              BackgroundSyncRegistration()));
+    active_registrations_.erase(sw_registration_id);
+    PostErrorResponse(BACKGROUND_SYNC_STATUS_STORAGE_ERROR, callback);
     return;
   }
 
@@ -527,49 +550,52 @@ void BackgroundSyncManager::RegisterDidStore(
     LOG(ERROR) << "BackgroundSync failed to store registration due to backend "
                   "failure.";
     BackgroundSyncMetrics::CountRegister(
-        new_registration.options()->periodicity, registration_could_fire,
+        new_registration->options()->periodicity, registration_could_fire,
         BackgroundSyncMetrics::REGISTRATION_IS_NOT_DUPLICATE,
         BACKGROUND_SYNC_STATUS_STORAGE_ERROR);
-    DisableAndClearManager(base::Bind(callback,
-                                      BACKGROUND_SYNC_STATUS_STORAGE_ERROR,
-                                      BackgroundSyncRegistration()));
+    DisableAndClearManager(base::Bind(
+        callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR,
+        base::Passed(scoped_ptr<BackgroundSyncRegistrationHandle>().Pass())));
     return;
   }
 
   BackgroundSyncMetrics::CountRegister(
-      new_registration.options()->periodicity, registration_could_fire,
+      new_registration->options()->periodicity, registration_could_fire,
       BackgroundSyncMetrics::REGISTRATION_IS_NOT_DUPLICATE,
       BACKGROUND_SYNC_STATUS_OK);
   FireReadyEvents();
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,
-      base::Bind(callback, BACKGROUND_SYNC_STATUS_OK, new_registration));
+      base::Bind(
+          callback, BACKGROUND_SYNC_STATUS_OK,
+          base::Passed(
+              CreateRegistrationHandle(new_registration_ref.get()).Pass())));
 }
 
-void BackgroundSyncManager::RemoveRegistrationFromMap(
+void BackgroundSyncManager::RemoveActiveRegistration(
     int64 sw_registration_id,
     const RegistrationKey& registration_key) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
-  DCHECK(LookupRegistration(sw_registration_id, registration_key));
+  DCHECK(LookupActiveRegistration(sw_registration_id, registration_key));
 
   BackgroundSyncRegistrations* registrations =
-      &sw_to_registrations_map_[sw_registration_id];
+      &active_registrations_[sw_registration_id];
 
   registrations->registration_map.erase(registration_key);
 }
 
-void BackgroundSyncManager::AddRegistrationToMap(
+void BackgroundSyncManager::AddActiveRegistration(
     int64 sw_registration_id,
     const GURL& origin,
-    const BackgroundSyncRegistration& sync_registration) {
+    const scoped_refptr<RefCountedRegistration>& sync_registration) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
-  DCHECK(sync_registration.IsValid());
+  DCHECK(sync_registration->value()->IsValid());
 
   BackgroundSyncRegistrations* registrations =
-      &sw_to_registrations_map_[sw_registration_id];
+      &active_registrations_[sw_registration_id];
   registrations->origin = origin;
 
-  RegistrationKey registration_key(sync_registration);
+  RegistrationKey registration_key(*sync_registration->value());
   registrations->registration_map[registration_key] = sync_registration;
 }
 
@@ -596,13 +622,75 @@ void BackgroundSyncManager::GetDataFromBackend(
 }
 
 void BackgroundSyncManager::FireOneShotSync(
-    const BackgroundSyncRegistration& registration,
+    BackgroundSyncRegistrationHandle::HandleId handle_id,
     const scoped_refptr<ServiceWorkerVersion>& active_version,
     const ServiceWorkerVersion::StatusCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(active_version);
+
+  // The ServiceWorkerVersion doesn't know when the client (javascript) is done
+  // with the registration so don't give it a BackgroundSyncRegistrationHandle.
+  // Once the render process gets the handle_id it can create its own handle
+  // (with a new unique handle id).
+  active_version->DispatchSyncEvent(handle_id, callback);
+}
 
-  active_version->DispatchSyncEvent(
-      mojo::ConvertTo<SyncRegistrationPtr>(registration), callback);
+scoped_ptr<BackgroundSyncRegistrationHandle>
+BackgroundSyncManager::CreateRegistrationHandle(
+    RefCountedRegistration* registration) {

[michaeln, 2015/08/28 02:53:11]

i think const scoped_refptr<T>& registration for this parameter instead of the
raw ptr is our current convention for passing around refcounted objs

[jkarlin, 2015/09/02 23:51:40]

Done.

+  scoped_refptr<RefCountedRegistration>* ptr =
+      new scoped_refptr<RefCountedRegistration>(registration);
+
+  // Registration handles have unique handle ids. The handle id maps to an
+  // internal RefCountedRegistration (which has the persistent registration id)
+  // via
+  // registration_reference_ids_.
+  BackgroundSyncRegistrationHandle::HandleId handle_id =
+      registration_handle_ids_.Add(ptr);
+
+  return make_scoped_ptr(new BackgroundSyncRegistrationHandle(
+      weak_ptr_factory_.GetWeakPtr(), handle_id));
+}
+
+BackgroundSyncRegistration* BackgroundSyncManager::GetRegistrationForHandle(
+    BackgroundSyncRegistrationHandle::HandleId handle_id) const {
+  scoped_refptr<RefCountedRegistration>* ref_registration =
+      registration_handle_ids_.Lookup(handle_id);
+  if (!ref_registration)
+    return nullptr;
+  return (*ref_registration)->value();
+}
+
+void BackgroundSyncManager::ReleaseRegistrationHandle(
+    BackgroundSyncRegistrationHandle::HandleId handle_id) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(registration_handle_ids_.Lookup(handle_id));
+  registration_handle_ids_.Remove(handle_id);
+}
+
+void BackgroundSyncManager::Unregister(
+    int64 sw_registration_id,

[michaeln, 2015/08/28 02:53:11]

I was wondering if sw_registration_id is needed? I see it being passed in
parallel with the handle_id often and now i see why. The
BackgroundSyncRegistration struct doesn't have a data member for the sw_reg_id
from whence it came. The value actually is needed here to remove it form the
active collection and to update storage properly. It might be nice to add that
value to the struct so |handle_id| is all you need to get to everything there is
to know about a particular registration.

[jkarlin, 2015/09/02 23:51:40]

Acknowledged.

+    SyncPeriodicity periodicity,
+    BackgroundSyncRegistrationHandle::HandleId handle_id,
+    const StatusCallback& callback) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  if (disabled_) {
+    BackgroundSyncMetrics::CountUnregister(
+        periodicity, BACKGROUND_SYNC_STATUS_STORAGE_ERROR);
+    base::ThreadTaskRunnerHandle::Get()->PostTask(
+        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR));
+    return;
+  }
+
+  BackgroundSyncRegistration* registration =
+      GetRegistrationForHandle(handle_id);
+  DCHECK(registration);
+
+  op_scheduler_.ScheduleOperation(base::Bind(
+      &BackgroundSyncManager::UnregisterImpl, weak_ptr_factory_.GetWeakPtr(),
+      sw_registration_id, RegistrationKey(*registration), registration->id(),
+      periodicity, MakeStatusCompletion(callback)));
 }
 
 void BackgroundSyncManager::UnregisterImpl(
@@ -621,10 +709,11 @@ void BackgroundSyncManager::UnregisterImpl(
     return;
   }
 
-  const BackgroundSyncRegistration* existing_registration =
-      LookupRegistration(sw_registration_id, registration_key);
+  const RefCountedRegistration* existing_registration =
+      LookupActiveRegistration(sw_registration_id, registration_key);
+
   if (!existing_registration ||
-      existing_registration->id() != sync_registration_id) {
+      existing_registration->value()->id() != sync_registration_id) {
     BackgroundSyncMetrics::CountUnregister(periodicity,
                                            BACKGROUND_SYNC_STATUS_NOT_FOUND);
     base::ThreadTaskRunnerHandle::Get()->PostTask(
@@ -632,7 +721,7 @@ void BackgroundSyncManager::UnregisterImpl(
     return;
   }
 
-  RemoveRegistrationFromMap(sw_registration_id, registration_key);
+  RemoveActiveRegistration(sw_registration_id, registration_key);
 
   StoreRegistrations(sw_registration_id,
                      base::Bind(&BackgroundSyncManager::UnregisterDidStore,
@@ -650,7 +739,7 @@ void BackgroundSyncManager::UnregisterDidStore(int64 sw_registration_id,
     // ServiceWorker was unregistered.
     BackgroundSyncMetrics::CountUnregister(
         periodicity, BACKGROUND_SYNC_STATUS_STORAGE_ERROR);
-    sw_to_registrations_map_.erase(sw_registration_id);
+    active_registrations_.erase(sw_registration_id);
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR));
     return;
@@ -678,24 +767,21 @@ void BackgroundSyncManager::GetRegistrationImpl(
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   if (disabled_) {
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR,
-                              BackgroundSyncRegistration()));
+    PostErrorResponse(BACKGROUND_SYNC_STATUS_STORAGE_ERROR, callback);
     return;
   }
 
-  const BackgroundSyncRegistration* out_registration =
-      LookupRegistration(sw_registration_id, registration_key);
-  if (!out_registration) {
-    base::ThreadTaskRunnerHandle::Get()->PostTask(
-        FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_NOT_FOUND,
-                              BackgroundSyncRegistration()));
+  RefCountedRegistration* registration =
+      LookupActiveRegistration(sw_registration_id, registration_key);
+  if (!registration) {
+    PostErrorResponse(BACKGROUND_SYNC_STATUS_NOT_FOUND, callback);
     return;
   }
 
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,
-      base::Bind(callback, BACKGROUND_SYNC_STATUS_OK, *out_registration));
+      base::Bind(callback, BACKGROUND_SYNC_STATUS_OK,
+                 base::Passed(CreateRegistrationHandle(registration).Pass())));
 }
 
 void BackgroundSyncManager::GetRegistrationsImpl(
@@ -704,31 +790,33 @@ void BackgroundSyncManager::GetRegistrationsImpl(
     const StatusAndRegistrationsCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
-  std::vector<BackgroundSyncRegistration> out_registrations;
+  scoped_ptr<ScopedVector<BackgroundSyncRegistrationHandle>> out_registrations(
+      new ScopedVector<BackgroundSyncRegistrationHandle>());
 
   if (disabled_) {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_STORAGE_ERROR,
-                              out_registrations));
+                              base::Passed(out_registrations.Pass())));
     return;
   }
 
   SWIdToRegistrationsMap::iterator it =
-      sw_to_registrations_map_.find(sw_registration_id);
+      active_registrations_.find(sw_registration_id);
 
-  if (it != sw_to_registrations_map_.end()) {
+  if (it != active_registrations_.end()) {
     const BackgroundSyncRegistrations& registrations = it->second;
     for (const auto& tag_and_registration : registrations.registration_map) {
-      const BackgroundSyncRegistration& registration =
-          tag_and_registration.second;
-      if (registration.options()->periodicity == periodicity)
-        out_registrations.push_back(registration);
+      RefCountedRegistration* registration = tag_and_registration.second.get();
+      if (registration->value()->options()->periodicity == periodicity) {
+        out_registrations->push_back(
+            CreateRegistrationHandle(registration).release());
+      }
     }
   }
 
   base::ThreadTaskRunnerHandle::Get()->PostTask(
-      FROM_HERE,
-      base::Bind(callback, BACKGROUND_SYNC_STATUS_OK, out_registrations));
+      FROM_HERE, base::Bind(callback, BACKGROUND_SYNC_STATUS_OK,
+                            base::Passed(out_registrations.Pass())));
 }
 
 bool BackgroundSyncManager::AreOptionConditionsMet(
@@ -758,11 +846,11 @@ void BackgroundSyncManager::SchedulePendingRegistrations() {
 #if defined(OS_ANDROID)
   bool keep_browser_alive_for_one_shot = false;
 
-  for (const auto& sw_id_and_registrations : sw_to_registrations_map_) {
+  for (const auto& sw_id_and_registrations : active_registrations_) {
     for (const auto& key_and_registration :
          sw_id_and_registrations.second.registration_map) {
       const BackgroundSyncRegistration& registration =
-          key_and_registration.second;
+          *key_and_registration.second->value();
       if (registration.sync_state() == SYNC_STATE_PENDING) {
         if (registration.options()->periodicity == SYNC_ONE_SHOT) {
           keep_browser_alive_for_one_shot = true;
@@ -808,11 +896,12 @@ void BackgroundSyncManager::FireReadyEventsImpl(const base::Closure& callback) {
   // Find the registrations that are ready to run.
   std::vector<std::pair<int64, RegistrationKey>> sw_id_and_keys_to_fire;
 
-  for (auto& sw_id_and_registrations : sw_to_registrations_map_) {
+  for (auto& sw_id_and_registrations : active_registrations_) {
     const int64 service_worker_id = sw_id_and_registrations.first;
     for (auto& key_and_registration :
          sw_id_and_registrations.second.registration_map) {
-      BackgroundSyncRegistration* registration = &key_and_registration.second;
+      BackgroundSyncRegistration* registration =
+          key_and_registration.second->value();
       if (IsRegistrationReadyToFire(*registration)) {
         sw_id_and_keys_to_fire.push_back(
             std::make_pair(service_worker_id, key_and_registration.first));
@@ -845,14 +934,15 @@ void BackgroundSyncManager::FireReadyEventsImpl(const base::Closure& callback) {
 
     for (const auto& sw_id_and_key : sw_id_and_keys_to_fire) {
       int64 service_worker_id = sw_id_and_key.first;
-      const BackgroundSyncRegistration* registration =
-          LookupRegistration(service_worker_id, sw_id_and_key.second);
+      const RefCountedRegistration* registration =
+          LookupActiveRegistration(service_worker_id, sw_id_and_key.second);
+      DCHECK(registration);
 
       service_worker_context_->FindRegistrationForId(
-          service_worker_id, sw_to_registrations_map_[service_worker_id].origin,
+          service_worker_id, active_registrations_[service_worker_id].origin,
           base::Bind(&BackgroundSyncManager::FireReadyEventsDidFindRegistration,
                      weak_ptr_factory_.GetWeakPtr(), sw_id_and_key.second,
-                     registration->id(), events_fired_barrier_closure,
+                     registration->value()->id(), events_fired_barrier_closure,
                      events_completed_barrier_closure));
     }
   }
@@ -877,15 +967,23 @@ void BackgroundSyncManager::FireReadyEventsDidFindRegistration(
     return;
   }
 
-  BackgroundSyncRegistration* registration =
-      LookupRegistration(service_worker_registration->id(), registration_key);
+  RefCountedRegistration* registration = LookupActiveRegistration(
+      service_worker_registration->id(), registration_key);
+  DCHECK(registration);
+
+  // Create a handle and keep it until the sync event completes. The client can
+  // acquire its own handle for longer-term use.
+  scoped_ptr<BackgroundSyncRegistrationHandle> registration_handle =
+      CreateRegistrationHandle(registration);
 
+  BackgroundSyncRegistrationHandle::HandleId handle_id =
+      registration_handle->handle_id();
   FireOneShotSync(
-      *registration, service_worker_registration->active_version(),
-      base::Bind(&BackgroundSyncManager::EventComplete,
-                 weak_ptr_factory_.GetWeakPtr(), service_worker_registration,
-                 service_worker_registration->id(), registration_key,
-                 registration_id, event_completed_callback));
+      handle_id, service_worker_registration->active_version(),
+      base::Bind(
+          &BackgroundSyncManager::EventComplete, weak_ptr_factory_.GetWeakPtr(),
+          service_worker_registration, service_worker_registration->id(),
+          base::Passed(registration_handle.Pass()), event_completed_callback));
 
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::Bind(event_fired_callback));
@@ -896,8 +994,7 @@ void BackgroundSyncManager::FireReadyEventsDidFindRegistration(
 void BackgroundSyncManager::EventComplete(
     const scoped_refptr<ServiceWorkerRegistration>& service_worker_registration,
     int64 service_worker_id,
-    const RegistrationKey& key,
-    BackgroundSyncRegistration::RegistrationId sync_registration_id,
+    scoped_ptr<BackgroundSyncRegistrationHandle> registration_handle,
     const base::Closure& callback,
     ServiceWorkerStatusCode status_code) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
@@ -906,14 +1003,13 @@ void BackgroundSyncManager::EventComplete(
 
   op_scheduler_.ScheduleOperation(base::Bind(
       &BackgroundSyncManager::EventCompleteImpl, weak_ptr_factory_.GetWeakPtr(),
-      service_worker_id, key, sync_registration_id, status_code,
+      service_worker_id, base::Passed(registration_handle.Pass()), status_code,
       MakeClosureCompletion(callback)));
 }
 
 void BackgroundSyncManager::EventCompleteImpl(
     int64 service_worker_id,
-    const RegistrationKey& key,
-    BackgroundSyncRegistration::RegistrationId sync_registration_id,
+    scoped_ptr<BackgroundSyncRegistrationHandle> registration_handle,
     ServiceWorkerStatusCode status_code,
     const base::Closure& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
@@ -925,12 +1021,8 @@ void BackgroundSyncManager::EventCompleteImpl(
   }
 
   BackgroundSyncRegistration* registration =
-      LookupRegistration(service_worker_id, key);
-  if (!registration || registration->id() != sync_registration_id) {
-    base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
-                                                  base::Bind(callback));
-    return;
-  }
+      registration_handle->registration();
+  DCHECK(registration);
 
   // The event ran to completion, we should count it, no matter what happens
   // from here.
@@ -943,8 +1035,13 @@ void BackgroundSyncManager::EventCompleteImpl(
       // this registration. (crbug.com/479665)
       registration->set_sync_state(SYNC_STATE_FAILED);
     } else {
-      registration = nullptr;
-      RemoveRegistrationFromMap(service_worker_id, key);
+      RegistrationKey key(*registration);
+      // Remove the registration if it's still active.
+      RefCountedRegistration* active_registration =
+          LookupActiveRegistration(service_worker_id, key);
+      if (active_registration &&
+          active_registration->value()->id() == registration->id())
+        RemoveActiveRegistration(service_worker_id, key);
     }
   } else {
     // TODO(jkarlin): Add support for running periodic syncs. (crbug.com/479674)
@@ -965,7 +1062,7 @@ void BackgroundSyncManager::EventCompleteDidStore(
 
   if (status_code == SERVICE_WORKER_ERROR_NOT_FOUND) {
     // The registration is gone.
-    sw_to_registrations_map_.erase(service_worker_id);
+    active_registrations_.erase(service_worker_id);
     base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
                                                   base::Bind(callback));
     return;
@@ -998,7 +1095,7 @@ void BackgroundSyncManager::OnRegistrationDeletedImpl(
 
   // The backend (ServiceWorkerStorage) will delete the data, so just delete the
   // memory representation here.
-  sw_to_registrations_map_.erase(registration_id);
+  active_registrations_.erase(registration_id);
   base::ThreadTaskRunnerHandle::Get()->PostTask(FROM_HERE,
                                                 base::Bind(callback));
 }
@@ -1006,7 +1103,7 @@ void BackgroundSyncManager::OnRegistrationDeletedImpl(
 void BackgroundSyncManager::OnStorageWipedImpl(const base::Closure& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
-  sw_to_registrations_map_.clear();
+  active_registrations_.clear();
   disabled_ = false;
   InitImpl(callback);
 }
@@ -1023,6 +1120,7 @@ void BackgroundSyncManager::OnPowerChanged() {
   FireReadyEvents();
 }
 
+// TODO(jkarlin): Figure out how to pass scoped_ptrs with this.
 template <typename CallbackT, typename... Params>
 void BackgroundSyncManager::CompleteOperationCallback(const CallbackT& callback,
                                                       Params... parameters) {
@@ -1032,6 +1130,27 @@ void BackgroundSyncManager::CompleteOperationCallback(const CallbackT& callback,
   op_scheduler_.CompleteOperationAndRunNext();
 }
 
+void BackgroundSyncManager::CompleteStatusAndRegistrationCallback(
+    StatusAndRegistrationCallback callback,
+    BackgroundSyncStatus status,
+    scoped_ptr<BackgroundSyncRegistrationHandle> registration_handle) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  callback.Run(status, registration_handle.Pass());
+  op_scheduler_.CompleteOperationAndRunNext();
+}
+
+void BackgroundSyncManager::CompleteStatusAndRegistrationsCallback(
+    StatusAndRegistrationsCallback callback,
+    BackgroundSyncStatus status,
+    scoped_ptr<ScopedVector<BackgroundSyncRegistrationHandle>>
+        registration_handles) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+
+  callback.Run(status, registration_handles.Pass());
+  op_scheduler_.CompleteOperationAndRunNext();
+}
+
 base::Closure BackgroundSyncManager::MakeEmptyCompletion() {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
@@ -1052,10 +1171,9 @@ BackgroundSyncManager::MakeStatusAndRegistrationCompletion(
     const StatusAndRegistrationCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
-  return base::Bind(&BackgroundSyncManager::CompleteOperationCallback<
-                        StatusAndRegistrationCallback, BackgroundSyncStatus,
-                        const BackgroundSyncRegistration&>,
-                    weak_ptr_factory_.GetWeakPtr(), callback);
+  return base::Bind(
+      &BackgroundSyncManager::CompleteStatusAndRegistrationCallback,
+      weak_ptr_factory_.GetWeakPtr(), callback);
 }
 
 BackgroundSyncManager::StatusAndRegistrationsCallback
@@ -1063,10 +1181,9 @@ BackgroundSyncManager::MakeStatusAndRegistrationsCompletion(
     const StatusAndRegistrationsCallback& callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
-  return base::Bind(&BackgroundSyncManager::CompleteOperationCallback<
-                        StatusAndRegistrationsCallback, BackgroundSyncStatus,
-                        const std::vector<BackgroundSyncRegistration>&>,
-                    weak_ptr_factory_.GetWeakPtr(), callback);
+  return base::Bind(
+      &BackgroundSyncManager::CompleteStatusAndRegistrationsCallback,
+      weak_ptr_factory_.GetWeakPtr(), callback);
 }
 
 BackgroundSyncManager::StatusCallback