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As the comment in assistant_query.h by dmblack@,
rename AssistantQueryType::kEmpty to kNull and rename AssistantEmptyQuery
to AssistantNullQuery.
Signed-off-by: Zhuoyu Qian <zhuoyu.qian@samsung.com>
Change-Id: Ic4948122bef5a90b7e3bbeae13655bc36223f971
Reviewed-on: https://chromium-review.googlesource.com/1170709Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582804}