Clean up TRequest in DataDecoderService class

This CL cleans up TRequest that is left in only DataDecoderService
class with the conversion to new mojo types

Bug: 955171
Change-Id: I28cd8a4f75c66df03a7bccffc922ce6a749a62ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1794323
Commit-Queue: Miyoung Shin <myid.shin@igalia.com>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Oksana Zhuravlova <oksamyt@chromium.org>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695618}
3 files changed