Revert r148496 "Refactor sync-specific parts out of SyncNotifier/SyncNotifierObserver"

It broke sync_integration_tests:
TwoClientExtensionSettingsAndAppSettingsSyncTest.AppsStartWithSameSettings
TwoClientExtensionSettingsAndAppSettingsSyncTest.AppsStartWithDifferentSettings

TBR=dcheng@chromium.org

BUG=
TEST=

Review URL: https://chromiumcodereview.appspot.com/10823037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148536 0039d316-1c4b-4281-b951-d872f2087c98

21 files changed, 195 insertions, 540 deletions

diff --git a/sync/notifier/chrome_invalidation_client.h b/sync/notifier/chrome_invalidation_client.h
index 2328f99a..ddd5bb0 100644
--- a/sync/notifier/chrome_invalidation_client.h
+++ b/sync/notifier/chrome_invalidation_client.h
@@ -8,6 +8,7 @@
 #ifndef SYNC_NOTIFIER_CHROME_INVALIDATION_CLIENT_H_
 #define SYNC_NOTIFIER_CHROME_INVALIDATION_CLIENT_H_
 
+#include <map>
 #include <string>
 
 #include "base/basictypes.h"
@@ -20,8 +21,8 @@
 #include "sync/internal_api/public/util/weak_handle.h"
 #include "sync/notifier/chrome_system_resources.h"
 #include "sync/notifier/invalidation_state_tracker.h"
+#include "sync/notifier/invalidation_util.h"
 #include "sync/notifier/notifications_disabled_reason.h"
-#include "sync/notifier/object_id_payload_map.h"
 #include "sync/notifier/state_writer.h"
 
 namespace buzz {
@@ -36,6 +37,10 @@ namespace syncer {
 
 class RegistrationManager;
 
+typedef std::map<invalidation::ObjectId,
+                 std::string,
+                 ObjectIdLessThan> ObjectIdPayloadMap;
+
 // ChromeInvalidationClient is not thread-safe and lives on the sync
 // thread.
 class ChromeInvalidationClient
diff --git a/sync/notifier/invalidation_notifier.cc b/sync/notifier/invalidation_notifier.cc
index 3a72f32..0c629c6 100644
--- a/sync/notifier/invalidation_notifier.cc
+++ b/sync/notifier/invalidation_notifier.cc
@@ -34,10 +34,14 @@ InvalidationNotifier::~InvalidationNotifier() {
   DCHECK(CalledOnValidThread());
 }
 
-void InvalidationNotifier::UpdateRegisteredIds(SyncNotifierObserver* handler,
-                                               const ObjectIdSet& ids) {
+void InvalidationNotifier::AddObserver(SyncNotifierObserver* observer) {
   DCHECK(CalledOnValidThread());
-  invalidation_client_.RegisterIds(helper_.UpdateRegisteredIds(handler, ids));
+  observers_.AddObserver(observer);
+}
+
+void InvalidationNotifier::RemoveObserver(SyncNotifierObserver* observer) {
+  DCHECK(CalledOnValidThread());
+  observers_.RemoveObserver(observer);
 }
 
 void InvalidationNotifier::SetUniqueId(const std::string& unique_id) {
@@ -81,6 +85,22 @@ void InvalidationNotifier::UpdateCredentials(
   invalidation_client_.UpdateCredentials(email, token);
 }
 
+void InvalidationNotifier::UpdateEnabledTypes(ModelTypeSet enabled_types) {
+  DCHECK(CalledOnValidThread());
+  CHECK(!invalidation_client_id_.empty());
+  ObjectIdSet ids;
+  for (ModelTypeSet::Iterator it = enabled_types.First(); it.Good();
+       it.Inc()) {
+    invalidation::ObjectId id;
+    if (!RealModelTypeToObjectId(it.Get(), &id)) {
+      DLOG(WARNING) << "Invalid model type " << it.Get();
+      continue;
+    }
+    ids.insert(id);
+  }
+  invalidation_client_.RegisterIds(ids);
+}
+
 void InvalidationNotifier::SendNotification(ModelTypeSet changed_types) {
   DCHECK(CalledOnValidThread());
   // Do nothing.
@@ -88,18 +108,33 @@ void InvalidationNotifier::SendNotification(ModelTypeSet changed_types) {
 
 void InvalidationNotifier::OnInvalidate(const ObjectIdPayloadMap& id_payloads) {
   DCHECK(CalledOnValidThread());
-  helper_.DispatchInvalidationsToHandlers(id_payloads, REMOTE_NOTIFICATION);
+  // TODO(dcheng): This should probably be a utility function somewhere...
+  ModelTypePayloadMap type_payloads;
+  for (ObjectIdPayloadMap::const_iterator it = id_payloads.begin();
+       it != id_payloads.end(); ++it) {
+    ModelType model_type;
+    if (!ObjectIdToRealModelType(it->first, &model_type)) {
+      DLOG(WARNING) << "Invalid object ID: " << ObjectIdToString(it->first);
+      continue;
+    }
+    type_payloads[model_type] = it->second;
+  }
+  FOR_EACH_OBSERVER(
+      SyncNotifierObserver, observers_,
+      OnIncomingNotification(type_payloads, REMOTE_NOTIFICATION));
 }
 
 void InvalidationNotifier::OnNotificationsEnabled() {
   DCHECK(CalledOnValidThread());
-  helper_.EmitOnNotificationsEnabled();
+  FOR_EACH_OBSERVER(SyncNotifierObserver, observers_,
+                    OnNotificationsEnabled());
 }
 
 void InvalidationNotifier::OnNotificationsDisabled(
     NotificationsDisabledReason reason) {
   DCHECK(CalledOnValidThread());
-  helper_.EmitOnNotificationsDisabled(reason);
+  FOR_EACH_OBSERVER(SyncNotifierObserver, observers_,
+                    OnNotificationsDisabled(reason));
 }
 
 }  // namespace syncer
diff --git a/sync/notifier/invalidation_notifier.h b/sync/notifier/invalidation_notifier.h
index 8d74552..c287efb 100644
--- a/sync/notifier/invalidation_notifier.h
+++ b/sync/notifier/invalidation_notifier.h
@@ -17,13 +17,13 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/observer_list.h"
 #include "base/threading/non_thread_safe.h"
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/internal_api/public/util/weak_handle.h"
 #include "sync/notifier/chrome_invalidation_client.h"
 #include "sync/notifier/invalidation_state_tracker.h"
 #include "sync/notifier/sync_notifier.h"
-#include "sync/notifier/sync_notifier_helper.h"
 
 namespace notifier {
 class PushClient;
@@ -49,12 +49,13 @@ class InvalidationNotifier
   virtual ~InvalidationNotifier();
 
   // SyncNotifier implementation.
-  virtual void UpdateRegisteredIds(SyncNotifierObserver* handler,
-                                   const ObjectIdSet& ids) OVERRIDE;
+  virtual void AddObserver(SyncNotifierObserver* observer) OVERRIDE;
+  virtual void RemoveObserver(SyncNotifierObserver* observer) OVERRIDE;
   virtual void SetUniqueId(const std::string& unique_id) OVERRIDE;
   virtual void SetStateDeprecated(const std::string& state) OVERRIDE;
   virtual void UpdateCredentials(
       const std::string& email, const std::string& token) OVERRIDE;
+  virtual void UpdateEnabledTypes(ModelTypeSet enabled_types) OVERRIDE;
   virtual void SendNotification(ModelTypeSet changed_types) OVERRIDE;
 
   // ChromeInvalidationClient::Listener implementation.
@@ -75,8 +76,6 @@ class InvalidationNotifier
   };
   State state_;
 
-  SyncNotifierHelper helper_;
-
   // Passed to |invalidation_client_|.
   const InvalidationVersionMap initial_max_invalidation_versions_;
 
@@ -87,6 +86,9 @@ class InvalidationNotifier
   // Passed to |invalidation_client_|.
   const std::string client_info_;
 
+  // Our observers (which must live on the same thread).
+  ObserverList<SyncNotifierObserver> observers_;
+
   // The client ID to pass to |chrome_invalidation_client_|.
   std::string invalidation_client_id_;
 
diff --git a/sync/notifier/invalidation_notifier_unittest.cc b/sync/notifier/invalidation_notifier_unittest.cc
index 4a07678..b0b64c7 100644
--- a/sync/notifier/invalidation_notifier_unittest.cc
+++ b/sync/notifier/invalidation_notifier_unittest.cc
@@ -50,10 +50,11 @@ class InvalidationNotifierTest : public testing::Test {
             initial_invalidation_state,
             MakeWeakHandle(mock_tracker_.AsWeakPtr()),
             "fake_client_info"));
+    invalidation_notifier_->AddObserver(&mock_observer_);
   }
 
   void ResetNotifier() {
-    invalidation_notifier_->UpdateRegisteredIds(&mock_observer_, ObjectIdSet());
+    invalidation_notifier_->RemoveObserver(&mock_observer_);
     // Stopping the invalidation notifier stops its scheduler, which deletes any
     // pending tasks without running them.  Some tasks "run and delete" another
     // task, so they must be run in order to avoid leaking the inner task.
@@ -74,16 +75,15 @@ TEST_F(InvalidationNotifierTest, Basic) {
   CreateAndObserveNotifier("fake_state");
   InSequence dummy;
 
-  ModelTypeSet models(PREFERENCES, BOOKMARKS, AUTOFILL);
-  invalidation_notifier_->UpdateRegisteredIds(
-      &mock_observer_, ModelTypeSetToObjectIdSet(models));
+  ModelTypePayloadMap type_payloads;
+  type_payloads[PREFERENCES] = "payload";
+  type_payloads[BOOKMARKS] = "payload";
+  type_payloads[AUTOFILL] = "payload";
 
-  const ModelTypePayloadMap& type_payloads =
-      ModelTypePayloadMapFromEnumSet(models, "payload");
   EXPECT_CALL(mock_observer_, OnNotificationsEnabled());
-  EXPECT_CALL(mock_observer_, OnIncomingNotification(
-      ModelTypePayloadMapToObjectIdPayloadMap(type_payloads),
-      REMOTE_NOTIFICATION));
+  EXPECT_CALL(mock_observer_,
+              OnIncomingNotification(type_payloads,
+                                     REMOTE_NOTIFICATION));
   EXPECT_CALL(mock_observer_,
               OnNotificationsDisabled(TRANSIENT_NOTIFICATION_ERROR));
   EXPECT_CALL(mock_observer_,
@@ -99,8 +99,14 @@ TEST_F(InvalidationNotifierTest, Basic) {
 
   invalidation_notifier_->OnNotificationsEnabled();
 
-  invalidation_notifier_->OnInvalidate(
-      ModelTypePayloadMapToObjectIdPayloadMap(type_payloads));
+  ObjectIdPayloadMap id_payloads;
+  for (ModelTypePayloadMap::const_iterator it = type_payloads.begin();
+       it != type_payloads.end(); ++it) {
+    invalidation::ObjectId id;
+    ASSERT_TRUE(RealModelTypeToObjectId(it->first, &id));
+    id_payloads[id] = "payload";
+  }
+  invalidation_notifier_->OnInvalidate(id_payloads);
 
   invalidation_notifier_->OnNotificationsDisabled(
       TRANSIENT_NOTIFICATION_ERROR);
diff --git a/sync/notifier/invalidation_util.cc b/sync/notifier/invalidation_util.cc
index 5b18d66..0065b50 100644
--- a/sync/notifier/invalidation_util.cc
+++ b/sync/notifier/invalidation_util.cc
@@ -33,32 +33,6 @@ bool ObjectIdToRealModelType(const invalidation::ObjectId& object_id,
   return NotificationTypeToRealModelType(object_id.name(), model_type);
 }
 
-ObjectIdSet ModelTypeSetToObjectIdSet(const ModelTypeSet& model_types) {
-  ObjectIdSet ids;
-  for (ModelTypeSet::Iterator it = model_types.First(); it.Good(); it.Inc()) {
-    invalidation::ObjectId model_type_as_id;
-    if (!RealModelTypeToObjectId(it.Get(), &model_type_as_id)) {
-      DLOG(WARNING) << "Invalid model type " << it.Get();
-      continue;
-    }
-    ids.insert(model_type_as_id);
-  }
-  return ids;
-}
-
-ModelTypeSet ObjectIdSetToModelTypeSet(const ObjectIdSet& ids) {
-  ModelTypeSet model_types;
-  for (ObjectIdSet::const_iterator it = ids.begin(); it != ids.end(); ++it) {
-    ModelType model_type;
-    if (!ObjectIdToRealModelType(*it, &model_type)) {
-      DLOG(WARNING) << "Invalid object ID " << ObjectIdToString(*it);
-      continue;
-    }
-    model_types.Put(model_type);
-  }
-  return model_types;
-}
-
 std::string ObjectIdToString(
     const invalidation::ObjectId& object_id) {
   std::stringstream ss;
diff --git a/sync/notifier/invalidation_util.h b/sync/notifier/invalidation_util.h
index bc43523..1a706ef 100644
--- a/sync/notifier/invalidation_util.h
+++ b/sync/notifier/invalidation_util.h
@@ -34,9 +34,6 @@ bool RealModelTypeToObjectId(ModelType model_type,
 bool ObjectIdToRealModelType(const invalidation::ObjectId& object_id,
                              ModelType* model_type);
 
-ObjectIdSet ModelTypeSetToObjectIdSet(const ModelTypeSet& models);
-ModelTypeSet ObjectIdSetToModelTypeSet(const ObjectIdSet& ids);
-
 std::string ObjectIdToString(const invalidation::ObjectId& object_id);
 
 std::string InvalidationToString(
diff --git a/sync/notifier/mock_sync_notifier_observer.h b/sync/notifier/mock_sync_notifier_observer.h
index fc88c52..b3baeb9 100644
--- a/sync/notifier/mock_sync_notifier_observer.h
+++ b/sync/notifier/mock_sync_notifier_observer.h
@@ -20,7 +20,7 @@ class MockSyncNotifierObserver : public SyncNotifierObserver {
   MOCK_METHOD0(OnNotificationsEnabled, void());
   MOCK_METHOD1(OnNotificationsDisabled, void(NotificationsDisabledReason));
   MOCK_METHOD2(OnIncomingNotification,
-               void(const ObjectIdPayloadMap&, IncomingNotificationSource));
+               void(const ModelTypePayloadMap&, IncomingNotificationSource));
 };
 
 }  // namespace syncer
diff --git a/sync/notifier/non_blocking_invalidation_notifier.cc b/sync/notifier/non_blocking_invalidation_notifier.cc
index ac0f76a..6ec7849 100644
--- a/sync/notifier/non_blocking_invalidation_notifier.cc
+++ b/sync/notifier/non_blocking_invalidation_notifier.cc
@@ -33,10 +33,10 @@ class NonBlockingInvalidationNotifier::Core
       const WeakHandle<InvalidationStateTracker>& invalidation_state_tracker,
       const std::string& client_info);
   void Teardown();
-  void UpdateRegisteredIds(const ObjectIdSet& ids);
   void SetUniqueId(const std::string& unique_id);
   void SetStateDeprecated(const std::string& state);
   void UpdateCredentials(const std::string& email, const std::string& token);
+  void UpdateEnabledTypes(ModelTypeSet enabled_types);
 
   // SyncNotifierObserver implementation (all called on I/O thread by
   // InvalidationNotifier).
@@ -44,7 +44,7 @@ class NonBlockingInvalidationNotifier::Core
   virtual void OnNotificationsDisabled(
       NotificationsDisabledReason reason) OVERRIDE;
   virtual void OnIncomingNotification(
-      const ObjectIdPayloadMap& id_payloads,
+      const ModelTypePayloadMap& type_payloads,
       IncomingNotificationSource source) OVERRIDE;
 
  private:
@@ -89,22 +89,17 @@ void NonBlockingInvalidationNotifier::Core::Initialize(
           initial_invalidation_state,
           invalidation_state_tracker,
           client_info));
+  invalidation_notifier_->AddObserver(this);
 }
 
 
 void NonBlockingInvalidationNotifier::Core::Teardown() {
   DCHECK(network_task_runner_->BelongsToCurrentThread());
-  invalidation_notifier_->UpdateRegisteredIds(this, ObjectIdSet());
+  invalidation_notifier_->RemoveObserver(this);
   invalidation_notifier_.reset();
   network_task_runner_ = NULL;
 }
 
-void NonBlockingInvalidationNotifier::Core::UpdateRegisteredIds(
-    const ObjectIdSet& ids) {
-  DCHECK(network_task_runner_->BelongsToCurrentThread());
-  invalidation_notifier_->UpdateRegisteredIds(this, ids);
-}
-
 void NonBlockingInvalidationNotifier::Core::SetUniqueId(
     const std::string& unique_id) {
   DCHECK(network_task_runner_->BelongsToCurrentThread());
@@ -123,6 +118,12 @@ void NonBlockingInvalidationNotifier::Core::UpdateCredentials(
   invalidation_notifier_->UpdateCredentials(email, token);
 }
 
+void NonBlockingInvalidationNotifier::Core::UpdateEnabledTypes(
+    ModelTypeSet enabled_types) {
+  DCHECK(network_task_runner_->BelongsToCurrentThread());
+  invalidation_notifier_->UpdateEnabledTypes(enabled_types);
+}
+
 void NonBlockingInvalidationNotifier::Core::OnNotificationsEnabled() {
   DCHECK(network_task_runner_->BelongsToCurrentThread());
   delegate_observer_.Call(FROM_HERE,
@@ -137,11 +138,12 @@ void NonBlockingInvalidationNotifier::Core::OnNotificationsDisabled(
 }
 
 void NonBlockingInvalidationNotifier::Core::OnIncomingNotification(
-    const ObjectIdPayloadMap& id_payloads, IncomingNotificationSource source) {
+    const ModelTypePayloadMap& type_payloads,
+    IncomingNotificationSource source) {
   DCHECK(network_task_runner_->BelongsToCurrentThread());
   delegate_observer_.Call(FROM_HERE,
                           &SyncNotifierObserver::OnIncomingNotification,
-                          id_payloads,
+                          type_payloads,
                           source);
 }
 
@@ -183,19 +185,16 @@ NonBlockingInvalidationNotifier::~NonBlockingInvalidationNotifier() {
   }
 }
 
-void NonBlockingInvalidationNotifier::UpdateRegisteredIds(
-    SyncNotifierObserver* handler, const ObjectIdSet& ids) {
+void NonBlockingInvalidationNotifier::AddObserver(
+    SyncNotifierObserver* observer) {
   DCHECK(parent_task_runner_->BelongsToCurrentThread());
-  const ObjectIdSet& all_registered_ids =
-      helper_.UpdateRegisteredIds(handler, ids);
-  if (!network_task_runner_->PostTask(
-          FROM_HERE,
-          base::Bind(
-              &NonBlockingInvalidationNotifier::Core::UpdateRegisteredIds,
-              core_.get(),
-              all_registered_ids))) {
-    NOTREACHED();
-  }
+  observers_.AddObserver(observer);
+}
+
+void NonBlockingInvalidationNotifier::RemoveObserver(
+    SyncNotifierObserver* observer) {
+  DCHECK(parent_task_runner_->BelongsToCurrentThread());
+  observers_.RemoveObserver(observer);
 }
 
 void NonBlockingInvalidationNotifier::SetUniqueId(
@@ -232,6 +231,17 @@ void NonBlockingInvalidationNotifier::UpdateCredentials(
   }
 }
 
+void NonBlockingInvalidationNotifier::UpdateEnabledTypes(
+    ModelTypeSet enabled_types) {
+  DCHECK(parent_task_runner_->BelongsToCurrentThread());
+  if (!network_task_runner_->PostTask(
+          FROM_HERE,
+          base::Bind(&NonBlockingInvalidationNotifier::Core::UpdateEnabledTypes,
+                     core_.get(), enabled_types))) {
+    NOTREACHED();
+  }
+}
+
 void NonBlockingInvalidationNotifier::SendNotification(
     ModelTypeSet changed_types) {
   DCHECK(parent_task_runner_->BelongsToCurrentThread());
@@ -241,20 +251,23 @@ void NonBlockingInvalidationNotifier::SendNotification(
 
 void NonBlockingInvalidationNotifier::OnNotificationsEnabled() {
   DCHECK(parent_task_runner_->BelongsToCurrentThread());
-  helper_.EmitOnNotificationsEnabled();
+  FOR_EACH_OBSERVER(SyncNotifierObserver, observers_,
+                    OnNotificationsEnabled());
 }
 
 void NonBlockingInvalidationNotifier::OnNotificationsDisabled(
     NotificationsDisabledReason reason) {
   DCHECK(parent_task_runner_->BelongsToCurrentThread());
-  helper_.EmitOnNotificationsDisabled(reason);
+  FOR_EACH_OBSERVER(SyncNotifierObserver, observers_,
+                    OnNotificationsDisabled(reason));
 }
 
 void NonBlockingInvalidationNotifier::OnIncomingNotification(
-        const ObjectIdPayloadMap& id_payloads,
+        const ModelTypePayloadMap& type_payloads,
         IncomingNotificationSource source) {
   DCHECK(parent_task_runner_->BelongsToCurrentThread());
-  helper_.DispatchInvalidationsToHandlers(id_payloads, source);
+  FOR_EACH_OBSERVER(SyncNotifierObserver, observers_,
+                    OnIncomingNotification(type_payloads, source));
 }
 
 }  // namespace syncer
diff --git a/sync/notifier/non_blocking_invalidation_notifier.h b/sync/notifier/non_blocking_invalidation_notifier.h
index f76b37b..4756a81 100644
--- a/sync/notifier/non_blocking_invalidation_notifier.h
+++ b/sync/notifier/non_blocking_invalidation_notifier.h
@@ -14,11 +14,11 @@
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "jingle/notifier/base/notifier_options.h"
 #include "sync/internal_api/public/util/weak_handle.h"
 #include "sync/notifier/invalidation_state_tracker.h"
 #include "sync/notifier/sync_notifier.h"
-#include "sync/notifier/sync_notifier_helper.h"
 #include "sync/notifier/sync_notifier_observer.h"
 
 namespace base {
@@ -44,12 +44,13 @@ class NonBlockingInvalidationNotifier
   virtual ~NonBlockingInvalidationNotifier();
 
   // SyncNotifier implementation.
-  virtual void UpdateRegisteredIds(SyncNotifierObserver* handler,
-                                   const ObjectIdSet& ids) OVERRIDE;
+  virtual void AddObserver(SyncNotifierObserver* observer) OVERRIDE;
+  virtual void RemoveObserver(SyncNotifierObserver* observer) OVERRIDE;
   virtual void SetUniqueId(const std::string& unique_id) OVERRIDE;
   virtual void SetStateDeprecated(const std::string& state) OVERRIDE;
   virtual void UpdateCredentials(
       const std::string& email, const std::string& token) OVERRIDE;
+  virtual void UpdateEnabledTypes(ModelTypeSet enabled_types) OVERRIDE;
   virtual void SendNotification(ModelTypeSet changed_types) OVERRIDE;
 
   // SyncNotifierObserver implementation.
@@ -57,7 +58,7 @@ class NonBlockingInvalidationNotifier
   virtual void OnNotificationsDisabled(
       NotificationsDisabledReason reason) OVERRIDE;
   virtual void OnIncomingNotification(
-      const ObjectIdPayloadMap& id_payloads,
+      const ModelTypePayloadMap& type_payloads,
       IncomingNotificationSource source) OVERRIDE;
 
  private:
@@ -65,7 +66,8 @@ class NonBlockingInvalidationNotifier
 
   base::WeakPtrFactory<NonBlockingInvalidationNotifier> weak_ptr_factory_;
 
-  SyncNotifierHelper helper_;
+  // Our observers (which must live on the parent thread).
+  ObserverList<SyncNotifierObserver> observers_;
 
   // The real guts of NonBlockingInvalidationNotifier, which allows
   // this class to live completely on the parent thread.
diff --git a/sync/notifier/non_blocking_invalidation_notifier_unittest.cc b/sync/notifier/non_blocking_invalidation_notifier_unittest.cc
index 36f4532..7a30f58 100644
--- a/sync/notifier/non_blocking_invalidation_notifier_unittest.cc
+++ b/sync/notifier/non_blocking_invalidation_notifier_unittest.cc
@@ -8,7 +8,6 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/threading/thread.h"
-#include "google/cacheinvalidation/v2/types.pb.h"
 #include "jingle/notifier/base/fake_base_task.h"
 #include "net/url_request/url_request_test_util.h"
 #include "sync/internal_api/public/base/model_type.h"
@@ -46,10 +45,11 @@ class NonBlockingInvalidationNotifierTest : public testing::Test {
             std::string(),  // initial_invalidation_state
             MakeWeakHandle(base::WeakPtr<InvalidationStateTracker>()),
             "fake_client_info"));
+    invalidation_notifier_->AddObserver(&mock_observer_);
   }
 
   virtual void TearDown() {
-    invalidation_notifier_->UpdateRegisteredIds(&mock_observer_, ObjectIdSet());
+    invalidation_notifier_->RemoveObserver(&mock_observer_);
     invalidation_notifier_.reset();
     request_context_getter_ = NULL;
     io_thread_.Stop();
@@ -67,16 +67,15 @@ class NonBlockingInvalidationNotifierTest : public testing::Test {
 TEST_F(NonBlockingInvalidationNotifierTest, Basic) {
   InSequence dummy;
 
-  ModelTypeSet models(PREFERENCES, BOOKMARKS, AUTOFILL);
-  invalidation_notifier_->UpdateRegisteredIds(
-      &mock_observer_, ModelTypeSetToObjectIdSet(models));
+  ModelTypePayloadMap type_payloads;
+  type_payloads[PREFERENCES] = "payload";
+  type_payloads[BOOKMARKS] = "";
+  type_payloads[AUTOFILL] = "";
 
-  const ModelTypePayloadMap& type_payloads =
-      ModelTypePayloadMapFromEnumSet(models, "payload");
   EXPECT_CALL(mock_observer_, OnNotificationsEnabled());
-  EXPECT_CALL(mock_observer_, OnIncomingNotification(
-      ModelTypePayloadMapToObjectIdPayloadMap(type_payloads),
-      REMOTE_NOTIFICATION));
+  EXPECT_CALL(mock_observer_,
+              OnIncomingNotification(type_payloads,
+                                     REMOTE_NOTIFICATION));
   EXPECT_CALL(mock_observer_,
               OnNotificationsDisabled(TRANSIENT_NOTIFICATION_ERROR));
   EXPECT_CALL(mock_observer_,
@@ -87,9 +86,8 @@ TEST_F(NonBlockingInvalidationNotifierTest, Basic) {
   invalidation_notifier_->UpdateCredentials("foo@bar.com", "fake_token");
 
   invalidation_notifier_->OnNotificationsEnabled();
-  invalidation_notifier_->OnIncomingNotification(
-      ModelTypePayloadMapToObjectIdPayloadMap(type_payloads),
-      REMOTE_NOTIFICATION);
+  invalidation_notifier_->OnIncomingNotification(type_payloads,
+                                                 REMOTE_NOTIFICATION);
   invalidation_notifier_->OnNotificationsDisabled(
       TRANSIENT_NOTIFICATION_ERROR);
   invalidation_notifier_->OnNotificationsDisabled(
diff --git a/sync/notifier/object_id_payload_map.cc b/sync/notifier/object_id_payload_map.cc
deleted file mode 100644
index 179f8be..0000000
--- a/sync/notifier/object_id_payload_map.cc
+++ /dev/null
@@ -1,40 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sync/notifier/object_id_payload_map.h"
-
-namespace syncer {
-
-ModelTypePayloadMap ObjectIdPayloadMapToModelTypePayloadMap(
-    const ObjectIdPayloadMap& id_payloads) {
-  ModelTypePayloadMap types_with_payloads;
-  for (ObjectIdPayloadMap::const_iterator it = id_payloads.begin();
-       it != id_payloads.end(); ++it) {
-    ModelType model_type;
-    if (!ObjectIdToRealModelType(it->first, &model_type)) {
-      DLOG(WARNING) << "Invalid object ID: "
-                    << ObjectIdToString(it->first);
-      continue;
-    }
-    types_with_payloads[model_type] = it->second;
-  }
-  return types_with_payloads;
-}
-
-ObjectIdPayloadMap ModelTypePayloadMapToObjectIdPayloadMap(
-    const ModelTypePayloadMap& type_payloads) {
-  ObjectIdPayloadMap id_payloads;
-  for (ModelTypePayloadMap::const_iterator it = type_payloads.begin();
-       it != type_payloads.end(); ++it) {
-    invalidation::ObjectId id;
-    if (!RealModelTypeToObjectId(it->first, &id)) {
-      DLOG(WARNING) << "Invalid model type " << it->first;
-      continue;
-    }
-    id_payloads[id] = it->second;
-  }
-  return id_payloads;
-}
-
-}  // namespace syncer
diff --git a/sync/notifier/object_id_payload_map.h b/sync/notifier/object_id_payload_map.h
deleted file mode 100644
index 9205326..0000000
--- a/sync/notifier/object_id_payload_map.h
+++ /dev/null
@@ -1,29 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef SYNC_NOTIFIER_OBJECT_ID_PAYLOAD_MAP_H_
-#define SYNC_NOTIFIER_OBJECT_ID_PAYLOAD_MAP_H_
-
-#include <map>
-#include <string>
-
-#include "google/cacheinvalidation/include/types.h"
-#include "sync/internal_api/public/base/model_type_payload_map.h"
-#include "sync/notifier/invalidation_util.h"
-
-namespace syncer {
-
-typedef std::map<invalidation::ObjectId,
-                 std::string,
-                 ObjectIdLessThan> ObjectIdPayloadMap;
-
-// Converts between ObjectIdPayloadMaps and ModelTypePayloadMaps.
-ModelTypePayloadMap ObjectIdPayloadMapToModelTypePayloadMap(
-    const ObjectIdPayloadMap& id_payloads);
-ObjectIdPayloadMap ModelTypePayloadMapToObjectIdPayloadMap(
-    const ModelTypePayloadMap& type_payloads);
-
-}  // namespace syncer
-
-#endif  // HOME_DCHENG_SRC_CHROMIUM_SRC_SYNC_NOTIFIER_OBJECT_ID_PAYLOAD_MAP_H_
diff --git a/sync/notifier/p2p_notifier.cc b/sync/notifier/p2p_notifier.cc
index 5d5aeff..bb16f5e 100644
--- a/sync/notifier/p2p_notifier.cc
+++ b/sync/notifier/p2p_notifier.cc
@@ -12,7 +12,6 @@
 #include "base/values.h"
 #include "jingle/notifier/listener/push_client.h"
 #include "sync/internal_api/public/base/model_type_payload_map.h"
-#include "sync/notifier/invalidation_util.h"
 #include "sync/notifier/sync_notifier_observer.h"
 
 namespace syncer {
@@ -157,16 +156,14 @@ P2PNotifier::~P2PNotifier() {
   push_client_->RemoveObserver(this);
 }
 
-void P2PNotifier::UpdateRegisteredIds(SyncNotifierObserver* handler,
-                                      const ObjectIdSet& ids) {
-  const ModelTypeSet enabled_types = ObjectIdSetToModelTypeSet(
-      helper_.UpdateRegisteredIds(handler, ids));
-  const ModelTypeSet new_enabled_types =
-      Difference(enabled_types, enabled_types_);
-  const P2PNotificationData notification_data(
-      unique_id_, NOTIFY_SELF, new_enabled_types);
-  SendNotificationData(notification_data);
-  enabled_types_ = enabled_types;
+void P2PNotifier::AddObserver(SyncNotifierObserver* observer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  observer_list_.AddObserver(observer);
+}
+
+void P2PNotifier::RemoveObserver(SyncNotifierObserver* observer) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  observer_list_.RemoveObserver(observer);
 }
 
 void P2PNotifier::SetUniqueId(const std::string& unique_id) {
@@ -196,6 +193,16 @@ void P2PNotifier::UpdateCredentials(
   logged_in_ = true;
 }
 
+void P2PNotifier::UpdateEnabledTypes(ModelTypeSet enabled_types) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  const ModelTypeSet new_enabled_types =
+      Difference(enabled_types, enabled_types_);
+  enabled_types_ = enabled_types;
+  const P2PNotificationData notification_data(
+      unique_id_, NOTIFY_SELF, new_enabled_types);
+  SendNotificationData(notification_data);
+}
+
 void P2PNotifier::SendNotification(ModelTypeSet changed_types) {
   DCHECK(thread_checker_.CalledOnValidThread());
   const P2PNotificationData notification_data(
@@ -207,7 +214,9 @@ void P2PNotifier::OnNotificationsEnabled() {
   DCHECK(thread_checker_.CalledOnValidThread());
   bool just_turned_on = (notifications_enabled_ == false);
   notifications_enabled_ = true;
-  helper_.EmitOnNotificationsEnabled();
+  FOR_EACH_OBSERVER(
+      SyncNotifierObserver, observer_list_,
+      OnNotificationsEnabled());
   if (just_turned_on) {
     const P2PNotificationData notification_data(
         unique_id_, NOTIFY_SELF, enabled_types_);
@@ -218,7 +227,9 @@ void P2PNotifier::OnNotificationsEnabled() {
 void P2PNotifier::OnNotificationsDisabled(
     notifier::NotificationsDisabledReason reason) {
   DCHECK(thread_checker_.CalledOnValidThread());
-  helper_.EmitOnNotificationsDisabled(FromNotifierReason(reason));
+  FOR_EACH_OBSERVER(
+      SyncNotifierObserver, observer_list_,
+      OnNotificationsDisabled(FromNotifierReason(reason)));
 }
 
 void P2PNotifier::OnIncomingNotification(
@@ -255,11 +266,10 @@ void P2PNotifier::OnIncomingNotification(
     DVLOG(1) << "No enabled and changed types -- not emitting notification";
     return;
   }
-  const ModelTypePayloadMap& type_payloads = ModelTypePayloadMapFromEnumSet(
-      notification_data.GetChangedTypes(), std::string());
-  helper_.DispatchInvalidationsToHandlers(
-      ModelTypePayloadMapToObjectIdPayloadMap(type_payloads),
-      REMOTE_NOTIFICATION);
+  const ModelTypePayloadMap& type_payloads =
+      ModelTypePayloadMapFromEnumSet(types_to_notify, std::string());
+  FOR_EACH_OBSERVER(SyncNotifierObserver, observer_list_,
+                    OnIncomingNotification(type_payloads, REMOTE_NOTIFICATION));
 }
 
 void P2PNotifier::SendNotificationDataForTest(
diff --git a/sync/notifier/p2p_notifier.h b/sync/notifier/p2p_notifier.h
index d2de89d..a360f25 100644
--- a/sync/notifier/p2p_notifier.h
+++ b/sync/notifier/p2p_notifier.h
@@ -20,7 +20,6 @@
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/notifier/notifications_disabled_reason.h"
 #include "sync/notifier/sync_notifier.h"
-#include "sync/notifier/sync_notifier_helper.h"
 
 namespace notifier {
 class PushClient;
@@ -82,8 +81,9 @@ class P2PNotificationData {
   ModelTypeSet changed_types_;
 };
 
-class P2PNotifier : public SyncNotifier,
-                    public notifier::PushClientObserver {
+class P2PNotifier
+    : public SyncNotifier,
+      public notifier::PushClientObserver {
  public:
   // The |send_notification_target| parameter was added to allow us to send
   // self-notifications in some cases, but not others.  The value should be
@@ -96,12 +96,13 @@ class P2PNotifier : public SyncNotifier,
   virtual ~P2PNotifier();
 
   // SyncNotifier implementation
-  virtual void UpdateRegisteredIds(SyncNotifierObserver* handler,
-                                   const ObjectIdSet& ids) OVERRIDE;
+  virtual void AddObserver(SyncNotifierObserver* observer) OVERRIDE;
+  virtual void RemoveObserver(SyncNotifierObserver* observer) OVERRIDE;
   virtual void SetUniqueId(const std::string& unique_id) OVERRIDE;
   virtual void SetStateDeprecated(const std::string& state) OVERRIDE;
   virtual void UpdateCredentials(
       const std::string& email, const std::string& token) OVERRIDE;
+  virtual void UpdateEnabledTypes(ModelTypeSet enabled_types) OVERRIDE;
   virtual void SendNotification(ModelTypeSet changed_types) OVERRIDE;
 
   // PushClientObserver implementation.
@@ -119,7 +120,7 @@ class P2PNotifier : public SyncNotifier,
 
   base::ThreadChecker thread_checker_;
 
-  SyncNotifierHelper helper_;
+  ObserverList<SyncNotifierObserver> observer_list_;
 
   // The push client.
   scoped_ptr<notifier::PushClient> push_client_;
diff --git a/sync/notifier/p2p_notifier_unittest.cc b/sync/notifier/p2p_notifier_unittest.cc
index 28a73c9..055fd1b 100644
--- a/sync/notifier/p2p_notifier_unittest.cc
+++ b/sync/notifier/p2p_notifier_unittest.cc
@@ -8,7 +8,6 @@
 
 #include "jingle/notifier/listener/fake_push_client.h"
 #include "sync/internal_api/public/base/model_type.h"
-#include "sync/internal_api/public/base/model_type_payload_map.h"
 #include "sync/notifier/mock_sync_notifier_observer.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -28,14 +27,15 @@ class P2PNotifierTest : public testing::Test {
             scoped_ptr<notifier::PushClient>(fake_push_client_),
             NOTIFY_OTHERS),
         next_sent_notification_to_reflect_(0) {
+    p2p_notifier_.AddObserver(&mock_observer_);
   }
 
   virtual ~P2PNotifierTest() {
-    p2p_notifier_.UpdateRegisteredIds(&mock_observer_, ObjectIdSet());
+    p2p_notifier_.RemoveObserver(&mock_observer_);
   }
 
   ModelTypePayloadMap MakePayloadMap(ModelTypeSet types) {
-    return ModelTypePayloadMapFromEnumSet(types, std::string());
+    return ModelTypePayloadMapFromEnumSet(types, "");
   }
 
   // Simulate receiving all the notifications we sent out since last
@@ -142,13 +142,10 @@ TEST_F(P2PNotifierTest, P2PNotificationDataNonDefault) {
 TEST_F(P2PNotifierTest, NotificationsBasic) {
   ModelTypeSet enabled_types(BOOKMARKS, PREFERENCES);
 
-  p2p_notifier_.UpdateRegisteredIds(&mock_observer_,
-                                    ModelTypeSetToObjectIdSet(enabled_types));
-
   EXPECT_CALL(mock_observer_, OnNotificationsEnabled());
-  EXPECT_CALL(mock_observer_, OnIncomingNotification(
-      ModelTypePayloadMapToObjectIdPayloadMap(MakePayloadMap(enabled_types)),
-      REMOTE_NOTIFICATION));
+  EXPECT_CALL(mock_observer_,
+              OnIncomingNotification(MakePayloadMap(enabled_types),
+                                     REMOTE_NOTIFICATION));
 
   p2p_notifier_.SetUniqueId("sender");
 
@@ -166,6 +163,8 @@ TEST_F(P2PNotifierTest, NotificationsBasic) {
   EXPECT_EQ(kEmail, fake_push_client_->email());
   EXPECT_EQ(kToken, fake_push_client_->token());
 
+  p2p_notifier_.UpdateEnabledTypes(enabled_types);
+
   ReflectSentNotifications();
   fake_push_client_->EnableNotifications();
 
@@ -187,21 +186,17 @@ TEST_F(P2PNotifierTest, SendNotificationData) {
   ModelTypeSet changed_types(THEMES, APPS);
   ModelTypeSet expected_types(THEMES);
 
-  p2p_notifier_.UpdateRegisteredIds(&mock_observer_,
-                                    ModelTypeSetToObjectIdSet(enabled_types));
-
   const ModelTypePayloadMap& expected_payload_map =
       MakePayloadMap(expected_types);
 
   EXPECT_CALL(mock_observer_, OnNotificationsEnabled());
   EXPECT_CALL(mock_observer_,
-              OnIncomingNotification(
-                  ModelTypePayloadMapToObjectIdPayloadMap(
-                      MakePayloadMap(enabled_types)),
-                  REMOTE_NOTIFICATION));
+              OnIncomingNotification(MakePayloadMap(enabled_types),
+                                     REMOTE_NOTIFICATION));
 
   p2p_notifier_.SetUniqueId("sender");
   p2p_notifier_.UpdateCredentials("foo@bar.com", "fake_token");
+  p2p_notifier_.UpdateEnabledTypes(enabled_types);
 
   ReflectSentNotifications();
   fake_push_client_->EnableNotifications();
@@ -216,9 +211,8 @@ TEST_F(P2PNotifierTest, SendNotificationData) {
 
   // Should be propagated.
   Mock::VerifyAndClearExpectations(&mock_observer_);
-  EXPECT_CALL(mock_observer_, OnIncomingNotification(
-      ModelTypePayloadMapToObjectIdPayloadMap(expected_payload_map),
-      REMOTE_NOTIFICATION));
+  EXPECT_CALL(mock_observer_, OnIncomingNotification(expected_payload_map,
+                                                     REMOTE_NOTIFICATION));
   p2p_notifier_.SendNotificationDataForTest(
       P2PNotificationData("sender", NOTIFY_SELF, changed_types));
 
@@ -246,9 +240,8 @@ TEST_F(P2PNotifierTest, SendNotificationData) {
 
   // Should be propagated.
   Mock::VerifyAndClearExpectations(&mock_observer_);
-  EXPECT_CALL(mock_observer_, OnIncomingNotification(
-      ModelTypePayloadMapToObjectIdPayloadMap(expected_payload_map),
-      REMOTE_NOTIFICATION));
+  EXPECT_CALL(mock_observer_, OnIncomingNotification(expected_payload_map,
+                                                     REMOTE_NOTIFICATION));
   p2p_notifier_.SendNotificationDataForTest(
       P2PNotificationData("sender2", NOTIFY_OTHERS, changed_types));
 
@@ -263,9 +256,8 @@ TEST_F(P2PNotifierTest, SendNotificationData) {
 
   // Should be propagated.
   Mock::VerifyAndClearExpectations(&mock_observer_);
-  EXPECT_CALL(mock_observer_, OnIncomingNotification(
-      ModelTypePayloadMapToObjectIdPayloadMap(expected_payload_map),
-      REMOTE_NOTIFICATION));
+  EXPECT_CALL(mock_observer_, OnIncomingNotification(expected_payload_map,
+                                                     REMOTE_NOTIFICATION));
   p2p_notifier_.SendNotificationDataForTest(
       P2PNotificationData("sender", NOTIFY_ALL, changed_types));
 
@@ -273,9 +265,8 @@ TEST_F(P2PNotifierTest, SendNotificationData) {
 
   // Should be propagated.
   Mock::VerifyAndClearExpectations(&mock_observer_);
-  EXPECT_CALL(mock_observer_, OnIncomingNotification(
-      ModelTypePayloadMapToObjectIdPayloadMap(expected_payload_map),
-      REMOTE_NOTIFICATION));
+  EXPECT_CALL(mock_observer_, OnIncomingNotification(expected_payload_map,
+                                                     REMOTE_NOTIFICATION));
   p2p_notifier_.SendNotificationDataForTest(
       P2PNotificationData("sender2", NOTIFY_ALL, changed_types));
 
diff --git a/sync/notifier/sync_notifier.h b/sync/notifier/sync_notifier.h
index 369ced1..0c775f4 100644
--- a/sync/notifier/sync_notifier.h
+++ b/sync/notifier/sync_notifier.h
@@ -12,7 +12,6 @@
 #include <string>
 
 #include "sync/internal_api/public/base/model_type.h"
-#include "sync/notifier/invalidation_util.h"
 
 namespace syncer {
 class SyncNotifierObserver;
@@ -22,11 +21,8 @@ class SyncNotifier {
   SyncNotifier() {}
   virtual ~SyncNotifier() {}
 
-  // Updates the set of ObjectIds associated with a given |handler|. Passing an
-  // empty ObjectIdSet will unregister |handler|. If two different handlers
-  // attempt to register for the same object ID, the first registration wins.
-  virtual void UpdateRegisteredIds(SyncNotifierObserver* handler,
-                                   const ObjectIdSet& ids) = 0;
+  virtual void AddObserver(SyncNotifierObserver* observer) = 0;
+  virtual void RemoveObserver(SyncNotifierObserver* observer) = 0;
 
   // SetUniqueId must be called once, before any call to
   // UpdateCredentials.  |unique_id| should be a non-empty globally
@@ -44,6 +40,8 @@ class SyncNotifier {
   virtual void UpdateCredentials(
       const std::string& email, const std::string& token) = 0;
 
+  virtual void UpdateEnabledTypes(ModelTypeSet enabled_types) = 0;
+
   // This is here only to support the old p2p notification implementation,
   // which is still used by sync integration tests.
   // TODO(akalin): Remove this once we move the integration tests off p2p
diff --git a/sync/notifier/sync_notifier_factory_unittest.cc b/sync/notifier/sync_notifier_factory_unittest.cc
index 8036c1a..52fd505 100644
--- a/sync/notifier/sync_notifier_factory_unittest.cc
+++ b/sync/notifier/sync_notifier_factory_unittest.cc
@@ -60,9 +60,8 @@ TEST_F(SyncNotifierFactoryTest, Basic) {
   ASSERT_FALSE(notifier.get());
 #else
   ASSERT_TRUE(notifier.get());
-  ObjectIdSet ids = ModelTypeSetToObjectIdSet(ModelTypeSet(syncer::BOOKMARKS));
-  notifier->UpdateRegisteredIds(&mock_observer_, ids);
-  notifier->UpdateRegisteredIds(&mock_observer_, ObjectIdSet());
+  notifier->AddObserver(&mock_observer_);
+  notifier->RemoveObserver(&mock_observer_);
 #endif
 }
 
@@ -78,9 +77,8 @@ TEST_F(SyncNotifierFactoryTest, Basic_P2P) {
   ASSERT_FALSE(notifier.get());
 #else
   ASSERT_TRUE(notifier.get());
-  ObjectIdSet ids = ModelTypeSetToObjectIdSet(ModelTypeSet(syncer::BOOKMARKS));
-  notifier->UpdateRegisteredIds(&mock_observer_, ids);
-  notifier->UpdateRegisteredIds(&mock_observer_, ObjectIdSet());
+  notifier->AddObserver(&mock_observer_);
+  notifier->RemoveObserver(&mock_observer_);
 #endif
 }
 
diff --git a/sync/notifier/sync_notifier_helper.cc b/sync/notifier/sync_notifier_helper.cc
deleted file mode 100644
index af3b2ea..0000000
--- a/sync/notifier/sync_notifier_helper.cc
+++ /dev/null
@@ -1,95 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "sync/notifier/sync_notifier_helper.h"
-
-#include "base/logging.h"
-
-namespace syncer {
-
-SyncNotifierHelper::SyncNotifierHelper() {}
-SyncNotifierHelper::~SyncNotifierHelper() {}
-
-ObjectIdSet SyncNotifierHelper::UpdateRegisteredIds(
-    SyncNotifierObserver* handler, const ObjectIdSet& ids) {
-  if (ids.empty()) {
-    handlers_.RemoveObserver(handler);
-  } else if (!handlers_.HasObserver(handler)) {
-    handlers_.AddObserver(handler);
-  }
-
-  ObjectIdSet registered_ids(ids);
-  // Remove all existing entries for |handler| and fill |registered_ids| with
-  // the rest.
-  for (ObjectIdHandlerMap::iterator it = id_to_handler_map_.begin();
-       it != id_to_handler_map_.end(); ) {
-    if (it->second == handler) {
-      ObjectIdHandlerMap::iterator erase_it = it;
-      ++it;
-      id_to_handler_map_.erase(erase_it);
-    } else {
-      registered_ids.insert(it->first);
-      ++it;
-    }
-  }
-
-  // Now add the entries for |handler|. We keep track of the last insertion
-  // point so we only traverse the map once to insert all the new entries.
-  ObjectIdHandlerMap::iterator insert_it = id_to_handler_map_.begin();
-  for (ObjectIdSet::const_iterator it = ids.begin(); it != ids.end(); ++it) {
-    insert_it = id_to_handler_map_.insert(insert_it,
-                                          std::make_pair(*it, handler));
-    CHECK_EQ(handler, insert_it->second) << "Duplicate registration for "
-                                         << ObjectIdToString(insert_it->first);
-  }
-  if (logging::DEBUG_MODE) {
-    // The mapping shouldn't contain any handlers that aren't in |handlers_|.
-    for (ObjectIdHandlerMap::const_iterator it = id_to_handler_map_.begin();
-         it != id_to_handler_map_.end(); ++it) {
-      CHECK(handlers_.HasObserver(it->second));
-    }
-  }
-  return registered_ids;
-}
-
-void SyncNotifierHelper::DispatchInvalidationsToHandlers(
-    const ObjectIdPayloadMap& id_payloads,
-    IncomingNotificationSource source) {
-  typedef std::map<SyncNotifierObserver*, ObjectIdPayloadMap> DispatchMap;
-  DispatchMap dispatch_map;
-  for (ObjectIdPayloadMap::const_iterator it = id_payloads.begin();
-       it != id_payloads.end(); ++it) {
-    ObjectIdHandlerMap::const_iterator find_it =
-        id_to_handler_map_.find(it->first);
-    // If we get an invalidation with a source type that we can't map to an
-    // observer, just drop it--the observer was unregistered while the
-    // invalidation was in flight.
-    if (find_it == id_to_handler_map_.end())
-      continue;
-    dispatch_map[find_it->second].insert(*it);
-  }
-
-  if (handlers_.might_have_observers()) {
-    ObserverListBase<SyncNotifierObserver>::Iterator it(handlers_);
-    SyncNotifierObserver* handler = NULL;
-    while ((handler = it.GetNext()) != NULL) {
-      DispatchMap::const_iterator dispatch_it = dispatch_map.find(handler);
-      if (dispatch_it != dispatch_map.end()) {
-        handler->OnIncomingNotification(dispatch_it->second, source);
-      }
-    }
-  }
-}
-
-void SyncNotifierHelper::EmitOnNotificationsEnabled() {
-  FOR_EACH_OBSERVER(SyncNotifierObserver, handlers_, OnNotificationsEnabled());
-}
-
-void SyncNotifierHelper::EmitOnNotificationsDisabled(
-    NotificationsDisabledReason reason) {
-  FOR_EACH_OBSERVER(SyncNotifierObserver, handlers_,
-                    OnNotificationsDisabled(reason));
-}
-
-}  // namespace syncer
diff --git a/sync/notifier/sync_notifier_helper.h b/sync/notifier/sync_notifier_helper.h
deleted file mode 100644
index 28ff187..0000000
--- a/sync/notifier/sync_notifier_helper.h
+++ /dev/null
@@ -1,55 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef SYNC_NOTIFIER_SYNC_NOTIFIER_HELPER_H_
-#define SYNC_NOTIFIER_SYNC_NOTIFIER_HELPER_H_
-
-#include <map>
-
-#include "base/basictypes.h"
-#include "base/observer_list.h"
-#include "sync/notifier/invalidation_util.h"
-#include "sync/notifier/object_id_payload_map.h"
-#include "sync/notifier/sync_notifier_observer.h"
-
-namespace syncer {
-
-// A helper class for classes that want to implement the SyncNotifier interface.
-// It helps keep track of registered handlers and which object ID registrations
-// are associated with which handlers, so implementors can just reuse the logic
-// here to dispatch invalidations and other interesting notifications.
-class SyncNotifierHelper {
- public:
-  SyncNotifierHelper();
-  ~SyncNotifierHelper();
-
-  // Updates the set of ObjectIds associated with a given |handler|. Passing an
-  // empty ObjectIdSet will unregister |handler|. The return value is an
-  // ObjectIdSet containing values for all existing handlers.
-  ObjectIdSet UpdateRegisteredIds(SyncNotifierObserver* handler,
-                                  const ObjectIdSet& ids);
-
-  // Helper that sorts incoming invalidations into a bucket for each handler
-  // and then dispatches the batched invalidations to the corresponding handler.
-  void DispatchInvalidationsToHandlers(const ObjectIdPayloadMap& id_payloads,
-                                       IncomingNotificationSource source);
-
-  // Calls the given handler method for each handler that has registered IDs.
-  void EmitOnNotificationsEnabled();
-  void EmitOnNotificationsDisabled(NotificationsDisabledReason reason);
-
- private:
-  typedef std::map<invalidation::ObjectId,
-                   SyncNotifierObserver*,
-                   ObjectIdLessThan> ObjectIdHandlerMap;
-
-  ObserverList<SyncNotifierObserver> handlers_;
-  ObjectIdHandlerMap id_to_handler_map_;
-
-  DISALLOW_COPY_AND_ASSIGN(SyncNotifierHelper);
-};
-
-}  // namespace syncer
-
-#endif  // SYNC_NOTIFIER_SYNC_NOTIFIER_HELPER_H_
diff --git a/sync/notifier/sync_notifier_helper_unittest.cc b/sync/notifier/sync_notifier_helper_unittest.cc
deleted file mode 100644
index ba2d768..0000000
--- a/sync/notifier/sync_notifier_helper_unittest.cc
+++ /dev/null
@@ -1,156 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "google/cacheinvalidation/v2/types.pb.h"
-#include "sync/notifier/sync_notifier_helper.h"
-#include "sync/notifier/mock_sync_notifier_observer.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-using testing::StrictMock;
-
-namespace syncer {
-
-class SyncNotifierHelperTest : public testing::Test {
- protected:
-  SyncNotifierHelperTest()
-      : kObjectId1(ipc::invalidation::ObjectSource::TEST, "a"),
-        kObjectId2(ipc::invalidation::ObjectSource::TEST, "b"),
-        kObjectId3(ipc::invalidation::ObjectSource::TEST, "c") {
-  }
-
-  invalidation::ObjectId kObjectId1;
-  invalidation::ObjectId kObjectId2;
-  invalidation::ObjectId kObjectId3;
-};
-
-// Basic check that registrations are correctly updated for one handler.
-TEST_F(SyncNotifierHelperTest, Basic) {
-  SyncNotifierHelper helper;
-  StrictMock<MockSyncNotifierObserver> observer;
-  ObjectIdSet ids;
-  ids.insert(kObjectId1);
-  ids.insert(kObjectId2);
-  helper.UpdateRegisteredIds(&observer, ids);
-
-  ObjectIdPayloadMap dispatched_payloads;
-  dispatched_payloads[kObjectId1] = "1";
-  dispatched_payloads[kObjectId2] = "2";
-  dispatched_payloads[kObjectId3] = "3";
-
-  // A object ID with no registration should be ignored.
-  ObjectIdPayloadMap expected_payload1;
-  expected_payload1[kObjectId1] = "1";
-  expected_payload1[kObjectId2] = "2";
-  EXPECT_CALL(observer, OnIncomingNotification(expected_payload1,
-                                               REMOTE_NOTIFICATION));
-  helper.DispatchInvalidationsToHandlers(dispatched_payloads,
-                                         REMOTE_NOTIFICATION);
-
-  // Removed object IDs should not be notified, newly-added ones should.
-  ids.erase(kObjectId1);
-  ids.insert(kObjectId3);
-  helper.UpdateRegisteredIds(&observer, ids);
-
-  ObjectIdPayloadMap expected_payload2;
-  expected_payload2[kObjectId2] = "2";
-  expected_payload2[kObjectId3] = "3";
-  EXPECT_CALL(observer, OnIncomingNotification(expected_payload2,
-                                               REMOTE_NOTIFICATION));
-  helper.DispatchInvalidationsToHandlers(dispatched_payloads,
-                                         REMOTE_NOTIFICATION);
-}
-
-// Tests that we correctly bucket and dispatch invalidations on multiple objects
-// to the corresponding handlers.
-TEST_F(SyncNotifierHelperTest, MultipleHandlers) {
-  SyncNotifierHelper helper;
-  StrictMock<MockSyncNotifierObserver> observer;
-  ObjectIdSet ids;
-  ids.insert(kObjectId1);
-  ids.insert(kObjectId2);
-  helper.UpdateRegisteredIds(&observer, ids);
-  StrictMock<MockSyncNotifierObserver> observer2;
-  ObjectIdSet ids2;
-  ids2.insert(kObjectId3);
-  helper.UpdateRegisteredIds(&observer2, ids2);
-
-  ObjectIdPayloadMap expected_payload1;
-  expected_payload1[kObjectId1] = "1";
-  expected_payload1[kObjectId2] = "2";
-  EXPECT_CALL(observer, OnIncomingNotification(expected_payload1,
-                                               REMOTE_NOTIFICATION));
-  ObjectIdPayloadMap expected_payload2;
-  expected_payload2[kObjectId3] = "3";
-  EXPECT_CALL(observer2, OnIncomingNotification(expected_payload2,
-                                                REMOTE_NOTIFICATION));
-
-  ObjectIdPayloadMap dispatched_payloads;
-  dispatched_payloads[kObjectId1] = "1";
-  dispatched_payloads[kObjectId2] = "2";
-  dispatched_payloads[kObjectId3] = "3";
-  helper.DispatchInvalidationsToHandlers(dispatched_payloads,
-                                         REMOTE_NOTIFICATION);
-
-  // Also verify that the callbacks for OnNotificationsEnabled/Disabled work.
-  EXPECT_CALL(observer, OnNotificationsEnabled());
-  EXPECT_CALL(observer2, OnNotificationsEnabled());
-  EXPECT_CALL(observer,
-              OnNotificationsDisabled(TRANSIENT_NOTIFICATION_ERROR));
-  EXPECT_CALL(observer2,
-              OnNotificationsDisabled(TRANSIENT_NOTIFICATION_ERROR));
-  helper.EmitOnNotificationsEnabled();
-  helper.EmitOnNotificationsDisabled(TRANSIENT_NOTIFICATION_ERROR);
-}
-
-// Multiple registrations by different handlers on the same object ID should
-// cause a CHECK.
-TEST_F(SyncNotifierHelperTest, MultipleRegistration) {
-  SyncNotifierHelper helper;
-  StrictMock<MockSyncNotifierObserver> observer;
-  ObjectIdSet ids;
-  ids.insert(kObjectId1);
-  ids.insert(kObjectId2);
-  helper.UpdateRegisteredIds(&observer, ids);
-
-  StrictMock<MockSyncNotifierObserver> observer2;
-  EXPECT_DEATH({ helper.UpdateRegisteredIds(&observer2, ids); },
-               "Duplicate registration for .*");
-}
-
-// Make sure that passing an empty set to UpdateRegisteredIds clears the
-// corresponding entries for the handler.
-TEST_F(SyncNotifierHelperTest, EmptySetUnregisters) {
-  SyncNotifierHelper helper;
-  StrictMock<MockSyncNotifierObserver> observer;
-  ObjectIdSet ids;
-  ids.insert(kObjectId1);
-  ids.insert(kObjectId2);
-  helper.UpdateRegisteredIds(&observer, ids);
-  // Control observer.
-  StrictMock<MockSyncNotifierObserver> observer2;
-  ObjectIdSet ids2;
-  ids2.insert(kObjectId3);
-  helper.UpdateRegisteredIds(&observer2, ids2);
-  // Unregister the first observer. It should not receive any further callbacks.
-  helper.UpdateRegisteredIds(&observer, ObjectIdSet());
-
-  ObjectIdPayloadMap expected_payload2;
-  expected_payload2[kObjectId3] = "3";
-  EXPECT_CALL(observer2, OnIncomingNotification(expected_payload2,
-                                                REMOTE_NOTIFICATION));
-  EXPECT_CALL(observer2, OnNotificationsEnabled());
-  EXPECT_CALL(observer2,
-              OnNotificationsDisabled(TRANSIENT_NOTIFICATION_ERROR));
-
-  ObjectIdPayloadMap dispatched_payloads;
-  dispatched_payloads[kObjectId1] = "1";
-  dispatched_payloads[kObjectId2] = "2";
-  dispatched_payloads[kObjectId3] = "3";
-  helper.DispatchInvalidationsToHandlers(dispatched_payloads,
-                                         REMOTE_NOTIFICATION);
-  helper.EmitOnNotificationsEnabled();
-  helper.EmitOnNotificationsDisabled(TRANSIENT_NOTIFICATION_ERROR);
-}
-
-}  // namespace syncer
diff --git a/sync/notifier/sync_notifier_observer.h b/sync/notifier/sync_notifier_observer.h
index b79f838..eaea91f 100644
--- a/sync/notifier/sync_notifier_observer.h
+++ b/sync/notifier/sync_notifier_observer.h
@@ -5,7 +5,7 @@
 #ifndef SYNC_NOTIFIER_SYNC_NOTIFIER_OBSERVER_H_
 #define SYNC_NOTIFIER_SYNC_NOTIFIER_OBSERVER_H_
 
-#include "sync/notifier/object_id_payload_map.h"
+#include "sync/internal_api/public/base/model_type_payload_map.h"
 #include "sync/notifier/notifications_disabled_reason.h"
 
 namespace syncer {
@@ -27,10 +27,10 @@ class SyncNotifierObserver {
   virtual void OnNotificationsDisabled(
       NotificationsDisabledReason reason) = 0;
 
-  // Called when a notification is received.  The per-id payloads
+  // Called when a notification is received.  The per-type payloads
   // are in |type_payloads| and the source is in |source|.
   virtual void OnIncomingNotification(
-      const ObjectIdPayloadMap& id_payloads,
+      const ModelTypePayloadMap& type_payloads,
       IncomingNotificationSource source) = 0;
 
  protected: