IndexedDB: Make IDBCursor.Advance() use native Mojo callback

IDBCursor.Advance() previously took a separate IDBCallbacks interface
that had its own lifecycle and could have a number of methods called
on it.

This change updates Advance() to use Mojo's native callback mechanism
so we can start moving away from the complicated IDBCallbacks
interface and instead use a simpler and easier to reason about async
response return approach.

Bug: 717812
Change-Id: Ia08bebfcafe5f63d60366e81b7f973b1e9ad2378
Commit-Queue: Chase Phillips <>
Reviewed-by: Tom Sepez <>
Reviewed-by: Victor Costan <>
Cr-Commit-Position: refs/heads/master@{#622176}
9 files changed