Threaded data provider: Support main thread data notifications (Chrome side)
The threaded data receiver will now receive notifications about received data packets on the main thread (needed for the progress indicator to work properly), and can optionally specify that it wants to receive a full copy of the data (needed when the Inspector is attached).
If a threaded data receiver is attached to a resource request, we also now make sure the resource completed message is bounced via the background thread, to make sure all data is received on the main thread first.
Blink side patch: https://codereview.chromium.org/
690793003
BUG=398076
Review URL: https://codereview.chromium.org/
689713004
Cr-Commit-Position: refs/heads/master@{#314704}