Use GData WAPI for FastFetch even if Drive API v2 is enabled.

chrome/browser/drive/drive_api_util.h

Index: chrome/browser/drive/drive_api_util.h
diff --git a/chrome/browser/drive/drive_api_util.h b/chrome/browser/drive/drive_api_util.h
index 118f223008389a61d4eb67fa2876f19cd3a38c87..2c9991d7db8679fedad17270fc1fc42d2b043802 100644
--- a/chrome/browser/drive/drive_api_util.h
+++ b/chrome/browser/drive/drive_api_util.h
@@ -62,6 +62,10 @@ void ParseShareUrlAndRun(const google_apis::GetShareUrlCallback& callback,
                          google_apis::GDataErrorCode error,
                          scoped_ptr<base::Value> value);
 
+// The resource ID for the root directory for WAPI is defined in the spec:
+// https://developers.google.com/google-apps/documents-list/
+extern const char kWapiRootDirectoryResourceId[];
+
 }  // namespace util
 }  // namespace drive