GitLab

Adding support for IDataRequestDeferral to the FakeDataTransferManager,
as well as adding a test-only PostDataRequested event for easily
intercepting the data shared by a DataRequested handler. Also expanding
the corresponding tests to validate this new behavior.

Bug: 1035527
Change-Id: I44589302272e432b3ea7201b50faa2d90d254194
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2500947Reviewed-by: Eric Willigers <ericwilligers@chromium.org>
Commit-Queue: Hoch Hochkeppel <mhochk@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#821431}