Remove knowledge of Chrome-specific SyncableService classes from WebDataService.

chrome/browser/webdata/web_data_service_base.cc

Index: chrome/browser/webdata/web_data_service_base.cc
diff --git a/chrome/browser/webdata/web_data_service_base.cc b/chrome/browser/webdata/web_data_service_base.cc
index 68650cf688e19ccf846aec8f73f76acd2eccaeae..3518349fffab41b116b3914b2ca7d9f3dbf985f8 100644
--- a/chrome/browser/webdata/web_data_service_base.cc
+++ b/chrome/browser/webdata/web_data_service_base.cc
@@ -40,6 +40,9 @@ WebDataServiceBase::WebDataServiceBase(const ProfileErrorCallback& callback)
 
 void WebDataServiceBase::ShutdownOnUIThread() {
   db_loaded_ = false;
+  BrowserThread::PostTask(
+      BrowserThread::DB, FROM_HERE,
+      base::Bind(&WebDataServiceBase::ShutdownOnDBThread, this));
   ShutdownDatabase();
 }
 
@@ -80,10 +83,22 @@ WebDatabase* WebDataServiceBase::GetDatabase() {
   return wdbs_->GetDatabaseOnDB();
 }
 
+base::SupportsUserData* WebDataServiceBase::GetDBUserData() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  if (!db_thread_user_data_)
+    db_thread_user_data_.reset(new base::SupportsUserData());
+  return db_thread_user_data_.get();
+}
+
 WebDataServiceBase::~WebDataServiceBase() {
   wdbs_.reset();
 }
 
+void WebDataServiceBase::ShutdownOnDBThread() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
+  db_thread_user_data_.reset();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 //
 // The following methods are executed on the DB thread.