Remove 1 ms rounding up of task delays on Windows
Remove 1 ms rounding up of task delays on Windows

Prior to a couple of attempts at fixing bug 487724 the message pump
would sometimes end up spinning for up to a ms when waiting for a
message's time to arrive. This was unintentional and non-obvious.

The eventual fix was to round up the delay time to the next ms.
Unfortunately this caused a regression in smoothness.top_25_smooth
which has not been resolved (investigation was delayed due to some
confusion about the results). Therefore this change reverts both
fix attempts in order to leave time for a proper investigation and
any necessary fixes.

It is worth mentioning that the delay introduced by rounding up to 1
ms is actually worse than expected on some operating systems. On Windows
7 a call to Sleep(1) will, if the timer frequency is raised, return
within a ms. On Windows 8.1 it will often take two ms to return, which
increases the delay. If the timer frequency is at its default interval
of 15.625 ms then the delay can be longer.

BUG=487724,497536

Review URL: https://codereview.chromium.org/1305873002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#344688}

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