The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e1961eae98ac4800590272448c8d28320d69ce1b

commit e1961eae98ac4800590272448c8d28320d69ce1b
Author: Jeffrey He <jeffreyhe@google.com>
Date: Thu Aug 10 15:22:35 2017

Make initial number of SchedulerWorkers be at most |worker_capacity_|.

The initial number of SchedulerWorkers created in
SchedulerWorkerPoolImpl::Start() used to be one more than the number of
tasks posted before Start() was called. This is incorrect because the
number of workers created here should not exceed the |worker_capacity_|
of the pool.

Bug:  754265 
Change-Id: Id14f68a8883c6e9ecf3a0a6f15d32d82a4f0bfda
Reviewed-on: https://chromium-review.googlesource.com/606108
Commit-Queue: Jeffrey He <jeffreyhe@google.com>
Reviewed-by: Gabriel Charette <gab@chromium.org>
Reviewed-by: Francois Doray <fdoray@chromium.org>
Reviewed-by: Robert Liao <robliao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#493396}
[modify] https://crrev.com/e1961eae98ac4800590272448c8d28320d69ce1b/base/task_scheduler/scheduler_worker_pool_impl.cc
[modify] https://crrev.com/e1961eae98ac4800590272448c8d28320d69ce1b/base/task_scheduler/scheduler_worker_pool_impl.h
[modify] https://crrev.com/e1961eae98ac4800590272448c8d28320d69ce1b/base/task_scheduler/scheduler_worker_pool_impl_unittest.cc