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This CL includes:
- Generate user intent based on text annotation result. Fallbacks to
generate translation intent based on language detection result if no
other intent is generated.
- Only send query to server if there is a supported intent generated.
- Rewrite query based on generated intent.
- Notify client with preprocess output. The output will be used to
conditionally trigger Quick Answers view in a follow up CL.

Bug: b/150249535
Test: unit tests
Change-Id: I702f1f65dd73bb8ff5d36fafb65e8409230d3028
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2198115Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Li Lin <llin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#769062}