drive: Add the local largest changestamp to chrome:drive-internals

chrome/browser/chromeos/drive/drive_file_system_interface.h

Index: chrome/browser/chromeos/drive/drive_file_system_interface.h
diff --git a/chrome/browser/chromeos/drive/drive_file_system_interface.h b/chrome/browser/chromeos/drive/drive_file_system_interface.h
index 1f26b3747b1af459d9841a14f6ac631b46cc09db..e6c8d3338d4598fa48c90db685f39328285df790 100644
--- a/chrome/browser/chromeos/drive/drive_file_system_interface.h
+++ b/chrome/browser/chromeos/drive/drive_file_system_interface.h
@@ -21,6 +21,7 @@ namespace drive {
 
 class DriveEntryProto;
 class DriveFileSystemObserver;
+class DriveResourceMetadata;
 
 typedef std::vector<DriveEntryProto> DriveEntryProtoVector;
 
@@ -346,6 +347,9 @@ class DriveFileSystemInterface {
                                scoped_ptr<gdata::DocumentEntry> entry,
                                const FilePath& file_content_path,
                                const base::Closure& callback) = 0;
+
+  // Returns the resource metadata associated with the file system.
+  virtual DriveResourceMetadata* GetResourceMetadata() = 0;
 };
 
 }  // namespace drive