Implement SyncEngine::DumpFiles()

chrome/browser/sync_file_system/drive_backend/metadata_database.h

Index: chrome/browser/sync_file_system/drive_backend/metadata_database.h
diff --git a/chrome/browser/sync_file_system/drive_backend/metadata_database.h b/chrome/browser/sync_file_system/drive_backend/metadata_database.h
index bcb9b1aa425ab8e7c37e171f2ac05f27c594c158..0668b069a7752f39f550f8ec01d952d1e36d6812 100644
--- a/chrome/browser/sync_file_system/drive_backend/metadata_database.h
+++ b/chrome/browser/sync_file_system/drive_backend/metadata_database.h
@@ -14,6 +14,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
+#include "base/values.h"
 #include "chrome/browser/sync_file_system/drive_backend/tracker_set.h"
 #include "chrome/browser/sync_file_system/sync_callbacks.h"
 #include "chrome/browser/sync_file_system/sync_status_code.h"
@@ -126,6 +127,9 @@ class MetadataDatabase {
   int64 GetSyncRootTrackerID() const;
   bool HasSyncRoot() const;
 
+  // Returns all file metadata for the given |app_id|.
+  scoped_ptr<base::ListValue> DumpFiles(const std::string& app_id);
+
   // Gets / updates the largest known change ID.
   // The largest known change ID is on-memory and not persist over restart.
   // This is supposed to use when a task fetches ChangeList in parallel to other