IndexedDB: Bind all renderer Mojo objects with the IndexedDB task runner

For browser->renderer interfaces, this change ensures that calls issued
by the browser will run in the renderer in the IndexedDB task queue task
runner.

For renderer->browser interfaces with no return calls, this change is
aesthetic.  The calls would have been issued by script running in a
context and would already have a high priority.

Eventually any Mojo interface method that takes a callback will be
updated to use Mojo's async callbacks.  This change means that, when
that happens, the Mojo task will run in the IDB task queue.

Bug: 717812, 913912
Change-Id: I976c36c33214652c2b6e0b4beecab2a1717c1d40
Reviewed-on: https://chromium-review.googlesource.com/c/1410171
Commit-Queue: Chase Phillips <cmp@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Hajime Hoshi <hajimehoshi@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623045}
15 files changed