[USS] Show USS counters in about:sync page

components/browser_sync/profile_sync_service.cc

Index: components/browser_sync/profile_sync_service.cc
diff --git a/components/browser_sync/profile_sync_service.cc b/components/browser_sync/profile_sync_service.cc
index 0b9152f3ca5e0f83cbf97a5e9fe344a67dbaac3c..ce6d0771e66cea59c00f4a4da75458c46cf4e20c 100644
--- a/components/browser_sync/profile_sync_service.cc
+++ b/components/browser_sync/profile_sync_service.cc
@@ -543,7 +543,7 @@ void ProfileSyncService::OnDirectoryTypeUpdateCounterUpdated(
                     OnUpdateCountersUpdated(type, counters));
 }
 
-void ProfileSyncService::OnDirectoryTypeStatusCounterUpdated(
+void ProfileSyncService::OnDatatypeStatusCounterUpdated(
     syncer::ModelType type,
     const syncer::StatusCounters& counters) {
   FOR_EACH_OBSERVER(syncer::TypeDebugInfoObserver, type_debug_info_observers_,
@@ -1807,7 +1807,7 @@ void ProfileSyncService::GetModelSafeRoutingInfo(
   }
 }
 
-base::Value* ProfileSyncService::GetTypeStatusMap() const {
+base::Value* ProfileSyncService::GetTypeStatusMap() {
   std::unique_ptr<base::ListValue> result(new base::ListValue());
 
   if (!backend_.get() || !backend_initialized_) {
@@ -1890,11 +1890,12 @@ base::Value* ProfileSyncService::GetTypeStatusMap() const {
       type_status->SetString("value", "Disabled by User");
     }
 
-    int live_count = detailed_status.num_entries_by_type[type] -
-                     detailed_status.num_to_delete_entries_by_type[type];
-    type_status->SetInteger("num_entries",
-                            detailed_status.num_entries_by_type[type]);
-    type_status->SetInteger("num_live", live_count);
+    const auto& dtc_iter = data_type_controllers_.find(type);
+    if (dtc_iter != data_type_controllers_.end()) {
+      dtc_iter->second->GetStatusCounters(
+          base::Bind(&ProfileSyncService::OnDatatypeStatusCounterUpdated,

[maxbogue, 2016/10/04 00:02:00]

If this Bind call were wrapped with syncer::BindToCurrentThread, then you would
be enforcing the asynchronous requirement from within this method, and you would
not need to PostTask in DirectoryDataTypeController or pass the task_runner to
post with to the SharedModelTypeProcessor.

You would definitely want to document this in the comment for
DataTypeController::GetStatusCounters though.

[Gang Wu, 2016/10/06 00:20:22]

Done.

+                     base::Unretained(this)));
+    }
 
     result->Append(std::move(type_status));
   }