gdata: Fix a bug that caused google drive not to load

chrome/browser/chromeos/gdata/gdata_files.cc

Index: chrome/browser/chromeos/gdata/gdata_files.cc
diff --git a/chrome/browser/chromeos/gdata/gdata_files.cc b/chrome/browser/chromeos/gdata/gdata_files.cc
index a1350d85e0e9529ee8473cf0cf037c8424a357d3..a7e9bfd7b2f23a194d4d9eadf789e0a3e7daf9a7 100644
--- a/chrome/browser/chromeos/gdata/gdata_files.cc
+++ b/chrome/browser/chromeos/gdata/gdata_files.cc
@@ -866,6 +866,15 @@ bool GDataRootDirectory::ParseFromString(const std::string& serialized_proto) {
       new GDataRootDirectoryProto());
   bool ok = proto->ParseFromString(serialized_proto);
   if (ok) {
+    // The title field for the root directory was originally empty, then
+    // changed to "gdata", then changed to "drive". Discard the proto data if
+    // the older formats are detected. See crbug.com/128133 for details.
+    const std::string& title = proto->gdata_directory().gdata_entry().title();
+    if (title != "drive") {
+      LOG(ERROR) << "Incompatible proto detected: " << title;
+      return false;
+    }
+
     FromProto(*proto.get());
     set_origin(FROM_CACHE);
     set_refresh_time(base::Time::Now());