Remove knowledge of Chrome-specific SyncableService classes from WebDataService.

chrome/browser/webdata/autocomplete_syncable_service.cc

Index: chrome/browser/webdata/autocomplete_syncable_service.cc
diff --git a/chrome/browser/webdata/autocomplete_syncable_service.cc b/chrome/browser/webdata/autocomplete_syncable_service.cc
index f039075cf83f2cfd69efb5373f1a1c92794ad1c5..88a7bc5c3ea9592846707dc501194dfd6931cd46 100644
--- a/chrome/browser/webdata/autocomplete_syncable_service.cc
+++ b/chrome/browser/webdata/autocomplete_syncable_service.cc
@@ -79,6 +79,26 @@ bool MergeTimestamps(const sync_pb::AutofillSpecifics& autofill,
   }
 }
 
+class DataObject : public base::SupportsUserData::Data {
+ public:
+  explicit DataObject(scoped_ptr<AutocompleteSyncableService> service)
+      : service_(service.Pass()) {
+  }
+
+  AutocompleteSyncableService* service() {
+    return service_.get();
+  }
+
+ private:
+  scoped_ptr<AutocompleteSyncableService> service_;
+
+  DISALLOW_COPY_AND_ASSIGN(DataObject);
+};
+
+void* DataKey() {
+  return reinterpret_cast<void*>(&AutocompleteSyncableService::AttachToWebData);
+}
+
 }  // namespace
 
 AutocompleteSyncableService::AutocompleteSyncableService(
@@ -96,6 +116,21 @@ AutocompleteSyncableService::~AutocompleteSyncableService() {
   DCHECK(CalledOnValidThread());
 }
 
+// static
+AutocompleteSyncableService* AutocompleteSyncableService::FromWebData(
+    WebDataServiceBase* service) {
+  return static_cast<DataObject*>(
+      service->GetDBUserData()->GetUserData(DataKey()))->service();
+}
+
+// static
+void AutocompleteSyncableService::AttachToWebData(
+    scoped_ptr<AutocompleteSyncableService> service,
+    WebDataServiceBase* web_data) {
+  web_data->GetDBUserData()->SetUserData(DataKey(),
+                                         new DataObject(service.Pass()));
+}
+
 AutocompleteSyncableService::AutocompleteSyncableService()
     : web_data_service_(NULL),
       cull_expired_entries_(false) {