gdrive: Get JSON feeds parsing off the UI thread.

chrome/browser/chromeos/gdata/gdata_operations.h

Index: chrome/browser/chromeos/gdata/gdata_operations.h
diff --git a/chrome/browser/chromeos/gdata/gdata_operations.h b/chrome/browser/chromeos/gdata/gdata_operations.h
index e0e78042858476b5f6f8c63437333291bcf1b062..c33c4dfaa22173bca1a50015b7ae4974f2e55d8f 100644
--- a/chrome/browser/chromeos/gdata/gdata_operations.h
+++ b/chrome/browser/chromeos/gdata/gdata_operations.h
@@ -253,7 +253,8 @@ class AuthorizeAppsOperation : public GetDataOperation {
 
   // Must override GetDataOperation's ParseResponse because the response is XML
   // not JSON.
-  virtual base::Value* ParseResponse(const std::string& data) OVERRIDE;
+  virtual bool ParseResponse(GDataErrorCode fetch_error_code,
+                             const std::string& data) OVERRIDE;
  private:
   std::string app_id_;
   GURL document_url_;