gdata: Make WeakPtrFactory the last parameter

chrome/browser/chromeos/gdata/operations_base.h

Index: chrome/browser/chromeos/gdata/operations_base.h
diff --git a/chrome/browser/chromeos/gdata/operations_base.h b/chrome/browser/chromeos/gdata/operations_base.h
index 4724fcac4c73447ccf99ea1d734ae75cc12b08f7..45fedf2407436e4d01c652b702a5d78051bc8a7b 100644
--- a/chrome/browser/chromeos/gdata/operations_base.h
+++ b/chrome/browser/chromeos/gdata/operations_base.h
@@ -206,6 +206,9 @@ class GetDataOperation : public UrlFetchOperationBase {
                     scoped_ptr<base::Value>* value);
 
   GetDataCallback callback_;
+
+  // Note: This should remain the last member so it'll be destroyed and
+  // invalidate its weak pointers before any other members are destroyed.
   base::WeakPtrFactory<GetDataOperation> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(GetDataOperation);
 };