[Sync] Replace uses of ObserverListThreadSafe with WeakHandles

chrome/browser/sync/notifier/non_blocking_invalidation_notifier.h

Index: chrome/browser/sync/notifier/non_blocking_invalidation_notifier.h
diff --git a/chrome/browser/sync/notifier/non_blocking_invalidation_notifier.h b/chrome/browser/sync/notifier/non_blocking_invalidation_notifier.h
index 351d67f37ad93d4bff827285301656d98c55881a..45da2f6e99a004e70d353949a06744df62eb3655 100644
--- a/chrome/browser/sync/notifier/non_blocking_invalidation_notifier.h
+++ b/chrome/browser/sync/notifier/non_blocking_invalidation_notifier.h
@@ -14,8 +14,11 @@
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
+#include "base/observer_list.h"
 #include "chrome/browser/sync/notifier/invalidation_version_tracker.h"
 #include "chrome/browser/sync/notifier/sync_notifier.h"
+#include "chrome/browser/sync/notifier/sync_notifier_observer.h"
 #include "chrome/browser/sync/util/weak_handle.h"
 #include "jingle/notifier/base/notifier_options.h"
 
@@ -25,7 +28,9 @@ class MessageLoopProxy;
 
 namespace sync_notifier {
 
-class NonBlockingInvalidationNotifier : public SyncNotifier {
+class NonBlockingInvalidationNotifier
+    : public SyncNotifier,
+      public SyncNotifierObserver {
  public:
   // |invalidation_version_tracker| must be initialized.
   NonBlockingInvalidationNotifier(
@@ -49,13 +54,26 @@ class NonBlockingInvalidationNotifier : public SyncNotifier {
   virtual void SendNotification(
       const syncable::ModelTypeSet& changed_types) OVERRIDE;
 
+  // SyncNotifierObserver implementation.
+  virtual void OnIncomingNotification(
+      const syncable::ModelTypePayloadMap& type_payloads) OVERRIDE;
+  virtual void OnNotificationStateChange(bool notifications_enabled) OVERRIDE;
+  virtual void StoreState(const std::string& state) OVERRIDE;
+
  private:
-  // The real guts of NonBlockingInvalidationNotifier, which allows this class
-  // to not be refcounted.
   class Core;
+
+  base::WeakPtrFactory<NonBlockingInvalidationNotifier> weak_ptr_factory_;
+
+  // 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.
   scoped_refptr<Core> core_;
   scoped_refptr<base::MessageLoopProxy> parent_message_loop_proxy_;
   scoped_refptr<base::MessageLoopProxy> io_message_loop_proxy_;
+
   DISALLOW_COPY_AND_ASSIGN(NonBlockingInvalidationNotifier);
 };