workers: Map the current thread-id to the WorkerRunLoop.

workers: Map the current thread-id to the WorkerRunLoop.

Instead of using an AtomicSequenceNumber to find an ID for a worker runloop,
use the ID of the current thread instead.

BUG=none
R=jochen@chromium.org

Committed: https://chromium.googlesource.com/chromium/src/+/3f8178aebed5980a64b6004eaa9358403c2693d7

[sadrul, 2015-01-28 18:58:16]

sadrul@chromium.org changed reviewers:
+ nasko@chromium.org

[sadrul, 2015-01-28 18:58:16]

Hi! Does this look like a reasonable change to make? If it is, then it would
allow us to remove WorkerTaskRunner::CurrentWorkerId(), and directly use
PlatformThread::CurrentId() in all the callsites instead.

[sadrul, 2015-01-28 23:52:43]

sadrul@chromium.org changed reviewers:
+ jochen@chromium.org

[sadrul, 2015-01-28 23:52:44]

+jochen@ too (since it looks like you reviewed nasko@'s previous changes in
WorkerTaskRunner)

[jochen (gone - plz use gerrit), 2015-01-29 15:12:01]

lgtm

[commit-bot: I haz the power, 2015-01-29 20:59:35]

Patchset 1 (id:??) landed as
https://crrev.com/3f8178aebed5980a64b6004eaa9358403c2693d7
Cr-Commit-Position: refs/heads/master@{#313786}

[sadrul, 2015-01-29 21:01:00]

Committed patchset #1 (id:1) manually as
3f8178aebed5980a64b6004eaa9358403c2693d7 (presubmit successful).