private void addIdToBundle(Bundle bundle) {
        if (mId != null) bundle.putParcelable(CustomTabsIntent.EXTRA_SESSION_ID, mId);
    }
Passes an URI of a file, e.g. in order to pass a large bitmap to be displayed in the
Custom Tabs provider.

Prior to calling this method, the client needs to grant a read permission to the target
Custom Tabs provider via {@link android.content.Context#grantUriPermission}.

The file is read and processed (where applicable) synchronously, therefore it's recommended
to call this method on a background thread.

@param uri {@link Uri} of the file.
@param purpose Purpose of transferring this file, one of the constants enumerated in
               {@code CustomTabsService#FilePurpose}.
@param extras Reserved for future use.
@return {@code true} if the file was received successfully.
customtabs/src/android/support/customtabs/CustomTabsSession.java