fix for high resolution timer on windows.

fix for high resolution timer on windows.

(merge to branch)

The CLs here
https://codereview.chromium.org/489793003
and here
https://codereview.chromium.org/395913006

In isolation look correct but taken together cause a overflow or underflow
bug. Basically the message loop was calling Time::ActivateHighResolutionTimer(false)
all the time (or very often) so the g_high_res_timer_count was underflowing
or overflowing.

Now messageloop only calls ActivateHighResolutionTimer in a balanced way.

This can make the base_unittests fail as well with
--gtest_filter=MessageLoopTest.HighResolutionTimer

BUG=153139
TEST=included, see bug for manual testing.

Review URL: https://codereview.chromium.org/541203002

Cr-Commit-Position: refs/heads/master@{#293434}
(cherry picked from commit 3365a510b17169457292bdb6144cc8b95fb7ea34)

Committed: https://chromium.googlesource.com/chromium/src/+/2a6f786b6a8a9f9f09ce0dd632e749e4f7ca1efd

[cpu_(ooo_6.6-7.5), 2014-09-16 02:08:17]

Committed patchset #1 (id:1) manually as 2a6f786.