Add 'Dump Database' tab to syncfs-internals (only for v2 for now)

chrome/browser/sync_file_system/drive_backend/sync_engine.cc

Index: chrome/browser/sync_file_system/drive_backend/sync_engine.cc
diff --git a/chrome/browser/sync_file_system/drive_backend/sync_engine.cc b/chrome/browser/sync_file_system/drive_backend/sync_engine.cc
index bdc37dc10e76477b59b1adfa3d623f65ed4ec7c0..070cc48b669f32c73c1a6dbd6cafe167865d6c5a 100644
--- a/chrome/browser/sync_file_system/drive_backend/sync_engine.cc
+++ b/chrome/browser/sync_file_system/drive_backend/sync_engine.cc
@@ -239,6 +239,12 @@ scoped_ptr<base::ListValue> SyncEngine::DumpFiles(const GURL& origin) {
   return metadata_database_->DumpFiles(origin.host());
 }
 
+scoped_ptr<base::ListValue> SyncEngine::DumpDatabase() {
+  if (!metadata_database_)
+    return scoped_ptr<base::ListValue>();
+  return metadata_database_->DumpDatabase();
+}
+
 void SyncEngine::SetSyncEnabled(bool enabled) {
   if (sync_enabled_ == enabled)
     return;