GitLab

Similar to the IDBCursor.Advance() commit 9a58b89a,
IDBCursor.CursorContinue() previously took a separate IDBCallbacks
interface that had its own lifecycle and could have a number of
methods called on it.

This CL updates CursorContinue() to use Mojo's native callback
mechanism.

Bug: 717812
Change-Id: Icc7d8b0be70a078f31d658ac9c35d83d8af12b0e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1480810
Commit-Queue: Chase Phillips <cmp@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638234}