[Sync] Replace TalkMediator delegate handling with thread-safe observer lists

Speculative fix for crash in bug.

BUG=chromium-os:7797
TEST=Manually with bug repro

Review URL: http://codereview.chromium.org/3837002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@62825 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 19 insertions, 54 deletions

diff --git a/chrome/browser/sync/notifier/server_notifier_thread.cc b/chrome/browser/sync/notifier/server_notifier_thread.cc
index 5251255..4c73445 100644
--- a/chrome/browser/sync/notifier/server_notifier_thread.cc
+++ b/chrome/browser/sync/notifier/server_notifier_thread.cc
@@ -19,10 +19,13 @@ ServerNotifierThread::ServerNotifierThread(
     const notifier::NotifierOptions& notifier_options,
     const std::string& state, StateWriter* state_writer)
     : notifier::MediatorThreadImpl(notifier_options),
-      state_(state), state_writer_(state_writer) {
+      state_(state),
+      state_writers_(new ObserverListThreadSafe<StateWriter>()),
+      state_writer_(state_writer) {
   DCHECK_EQ(notifier::NOTIFICATION_SERVER,
             notifier_options.notification_method);
   DCHECK(state_writer_);
+  state_writers_->AddObserver(state_writer_);
 }
 
 ServerNotifierThread::~ServerNotifierThread() {}
@@ -46,6 +49,7 @@ void ServerNotifierThread::SubscribeForUpdates(
 
 void ServerNotifierThread::Logout() {
   DCHECK_EQ(MessageLoop::current(), parent_message_loop_);
+  state_writers_->RemoveObserver(state_writer_);
   state_writer_ = NULL;
   worker_message_loop()->PostTask(
       FROM_HERE,
@@ -72,31 +76,23 @@ void ServerNotifierThread::OnInvalidate(syncable::ModelType model_type) {
     LOG(INFO) << "OnInvalidate: " << syncable::ModelTypeToString(model_type);
   }
   // TODO(akalin): Signal notification only for the invalidated types.
-  parent_message_loop_->PostTask(
-      FROM_HERE,
-      NewRunnableMethod(
-          this,
-          &ServerNotifierThread::SignalIncomingNotification));
+  // TODO(akalin): Fill this in with something meaningful.
+  IncomingNotificationData notification_data;
+  observers_->Notify(&Observer::OnIncomingNotification, notification_data);
 }
 
 void ServerNotifierThread::OnInvalidateAll() {
   DCHECK_EQ(MessageLoop::current(), worker_message_loop());
   LOG(INFO) << "OnInvalidateAll";
-  parent_message_loop_->PostTask(
-      FROM_HERE,
-      NewRunnableMethod(
-          this,
-          &ServerNotifierThread::SignalIncomingNotification));
+  // TODO(akalin): Fill this in with something meaningful.
+  IncomingNotificationData notification_data;
+  observers_->Notify(&Observer::OnIncomingNotification, notification_data);
 }
 
 void ServerNotifierThread::WriteState(const std::string& state) {
   DCHECK_EQ(MessageLoop::current(), worker_message_loop());
   VLOG(1) << "WriteState";
-  parent_message_loop_->PostTask(
-      FROM_HERE,
-      NewRunnableMethod(
-          this,
-          &ServerNotifierThread::SignalWriteState, state));
+  state_writers_->Notify(&StateWriter::WriteState, state);
 }
 
 void ServerNotifierThread::OnDisconnect() {
@@ -132,34 +128,7 @@ void ServerNotifierThread::RegisterTypesAndSignalSubscribed() {
     return;
   }
   chrome_invalidation_client_->RegisterTypes();
-  parent_message_loop_->PostTask(
-      FROM_HERE,
-      NewRunnableMethod(
-          this,
-          &ServerNotifierThread::SignalSubscribed));
-}
-
-void ServerNotifierThread::SignalSubscribed() {
-  DCHECK_EQ(MessageLoop::current(), parent_message_loop_);
-  if (delegate_) {
-    delegate_->OnSubscriptionStateChange(true);
-  }
-}
-
-void ServerNotifierThread::SignalIncomingNotification() {
-  DCHECK_EQ(MessageLoop::current(), parent_message_loop_);
-  if (delegate_) {
-    // TODO(akalin): Fill this in with something meaningful.
-    IncomingNotificationData notification_data;
-    delegate_->OnIncomingNotification(notification_data);
-  }
-}
-
-void ServerNotifierThread::SignalWriteState(const std::string& state) {
-  DCHECK_EQ(MessageLoop::current(), parent_message_loop_);
-  if (state_writer_) {
-    state_writer_->WriteState(state);
-  }
+  observers_->Notify(&Observer::OnSubscriptionStateChange, true);
 }
 
 void ServerNotifierThread::StopInvalidationListener() {
diff --git a/chrome/browser/sync/notifier/server_notifier_thread.h b/chrome/browser/sync/notifier/server_notifier_thread.h
index 5e48379..76ec4f1 100644
--- a/chrome/browser/sync/notifier/server_notifier_thread.h
+++ b/chrome/browser/sync/notifier/server_notifier_thread.h
@@ -16,6 +16,8 @@
 #include <string>
 #include <vector>
 
+#include "base/observer_list_threadsafe.h"
+#include "base/ref_counted.h"
 #include "base/scoped_ptr.h"
 #include "chrome/browser/sync/notifier/chrome_invalidation_client.h"
 #include "chrome/browser/sync/notifier/state_writer.h"
@@ -73,21 +75,15 @@ class ServerNotifierThread
   // Posted to the worker thread by SubscribeForUpdates().
   void RegisterTypesAndSignalSubscribed();
 
-  // Signal to the delegate that we're subscribed.
-  void SignalSubscribed();
-
-  // Signal to the delegate that we have an incoming notification.
-  void SignalIncomingNotification();
-
-  // Signal to the delegate to write the state.
-  void SignalWriteState(const std::string& state);
-
   // Called by StartInvalidationListener() and posted to the worker
   // thread by Stop().
   void StopInvalidationListener();
 
   std::string state_;
-  // May be NULL.
+  // Hack to get the nice thread-safe behavior for |state_writer_|.
+  scoped_refptr<ObserverListThreadSafe<StateWriter> > state_writers_;
+  // We still need to keep |state_writer_| around to remove it from
+  // |state_writers_|.
   StateWriter* state_writer_;
   scoped_ptr<ChromeInvalidationClient> chrome_invalidation_client_;
 };