[USS] Show USS counters in about:sync page

components/sync/driver/directory_data_type_controller.cc

Index: components/sync/driver/directory_data_type_controller.cc
diff --git a/components/sync/driver/directory_data_type_controller.cc b/components/sync/driver/directory_data_type_controller.cc
index 62a1720ab5ecb0ba115c70a1d80ecd9cfdfd4ac8..cae851d7a70e45fc82fc1d5121887e509f9a2d81 100644
--- a/components/sync/driver/directory_data_type_controller.cc
+++ b/components/sync/driver/directory_data_type_controller.cc
@@ -4,6 +4,8 @@
 
 #include "components/sync/driver/directory_data_type_controller.h"
 
+#include "base/memory/ptr_util.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "components/sync/core/user_share.h"
 #include "components/sync/driver/backend_data_type_configurer.h"
 #include "components/sync/driver/sync_service.h"
@@ -33,6 +35,23 @@ void DirectoryDataTypeController::GetAllNodes(
   callback.Run(type(), std::move(node_list));
 }
 
+void DirectoryDataTypeController::GetStatusCounters(
+    const StatusCountersCallback& callback) {
+  std::vector<int> num_entries_by_type(syncer::MODEL_TYPE_COUNT, 0);
+  std::vector<int> num_to_delete_entries_by_type(syncer::MODEL_TYPE_COUNT, 0);
+  sync_client_->GetSyncService()
+      ->GetUserShare()
+      ->directory->CollectMetaHandleCounts(&num_entries_by_type,
+                                           &num_to_delete_entries_by_type);
+  std::unique_ptr<syncer::StatusCounters> counters =
+      base::MakeUnique<syncer::StatusCounters>();
+  counters->num_entries_and_tombstones = num_entries_by_type[type()];
+  counters->num_entries =
+      num_entries_by_type[type()] - num_to_delete_entries_by_type[type()];
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(callback, type(), base::Passed(&counters)));
+};
+
 void DirectoryDataTypeController::RegisterWithBackend(
     BackendDataTypeConfigurer* configurer) {}