[sync] Check for null pointers before calling |FinishConfigureDataTypesOnFrontendLoop| in sbh.

chrome/browser/sync/glue/sync_backend_host.cc

 // Copyright (c) 2011 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 "build/build_config.h"
 
 #include "chrome/browser/sync/glue/sync_backend_host.h"
 
 #include <algorithm>
 #include <map>
@@ skipping 688 matching lines @@
 void SyncBackendHost::Core::DeleteSyncDataFolder() {
   DCHECK_EQ(MessageLoop::current(), sync_loop_);
   if (file_util::DirectoryExists(host_->sync_data_folder_path())) {
     if (!file_util::Delete(host_->sync_data_folder_path(), true))
       SLOG(DFATAL) << "Could not delete the Sync Data folder.";
   }
 }
 
 void SyncBackendHost::Core::FinishConfigureDataTypes() {
   DCHECK_EQ(MessageLoop::current(), sync_loop_);
+  if (!host_ || !host_->frontend_)
+    return;
   host_->frontend_loop_->PostTask(FROM_HERE, base::Bind(
       &SyncBackendHost::Core::FinishConfigureDataTypesOnFrontendLoop, this));
 }
 
 void SyncBackendHost::Core::HandleInitializationCompletedOnFrontendLoop(
     const WeakHandle<JsBackend>& js_backend,
     bool success) {
   if (!host_)
     return;
   host_->HandleInitializationCompletedOnFrontendLoop(js_backend, success);
@@ skipping 152 matching lines @@
   host_->frontend_->OnClearServerDataSucceeded();
 }
 
 void SyncBackendHost::Core::HandleClearServerDataFailedOnFrontendLoop() {
   if (!host_ || !host_->frontend_)
     return;
   host_->frontend_->OnClearServerDataFailed();
 }
 
 void SyncBackendHost::Core::FinishConfigureDataTypesOnFrontendLoop() {
+  if (!host_)
+    return;
   host_->FinishConfigureDataTypesOnFrontendLoop();
 }
 
 void SyncBackendHost::AddExperimentalTypes() {
   CHECK(initialized());
   syncable::ModelTypeSet to_add;
   if (core_->sync_manager()->ReceivedExperimentalTypes(&to_add))
     frontend_->OnDataTypesChanged(to_add);
 }
 
@@ skipping 182 matching lines @@
       FROM_HERE,
       base::Bind(&SyncBackendHost::Core::DoRefreshEncryption,
                  core_.get(), sync_thread_done_callback));
 }
 
 #undef SVLOG
 
 #undef SLOG
 
 }  // namespace browser_sync