[cherrypick] Fix computation of runtime for throttled tasks

[cherrypick] Fix computation of runtime for throttled tasks

The computation of the delayed task runtime was computing the (virtual)
TimeDomain's now + delay.  That doesn't take into account the skew
between the real time and the virtual time, which meant timers could
run sooner than expected for background tabs.  Timers associated with
foreground tabs are unaffected.

This patch makes the computation of delayed runtime  the responsibility
of the TimeDomain and introduces a ThrottledTimeDomain which computes
the delayed runtime as realtime + delay.

This means timers will no longer run sooner than expected.  Under normal
circumstancs this only timers whose delay modulo 1000ms is less than 100
ms are less likely to be affected.  Timers whose whose delay modulo
1000ms is greater than 900 are highly likely to be affected (there's a
good chance their delay was too small before).

BUG=587074
Review URL: https://codereview.chromium.org/1718233002

Cr-Commit-Position: refs/heads/master@{#376993}
(cherry picked from commit b56bbe4ce3e7276a130a00d83cf00e5672cd6be1)

R=skyostil@chromium.org

Committed: https://chromium.googlesource.com/chromium/src/+/fd563254490ae93382cb88a1e9a1c1e54815c97b

[alex clarke (OOO till 29th), 2016-02-26 13:54:38]

Description was changed from

==========
[cherrypick] Fix computation of runtime for throttled tasks

The computation of the delayed task runtime was computing the (virtual)
TimeDomain's now + delay.  That doesn't take into account the skew
between the real time and the virtual time, which meant timers could
run sooner than expected for background tabs.  Timers associated with
foreground tabs are unaffected.

This patch makes the computation of delayed runtime  the responsibility
of the TimeDomain and introduces a ThrottledTimeDomain which computes
the delayed runtime as realtime + delay.

This means timers will no longer run sooner than expected.  Under normal
circumstancs this only timers whose delay modulo 1000ms is less than 100
ms are less likely to be affected.  Timers whose whose delay modulo
1000ms is greater than 900 are highly likely to be affected (there's a
good chance their delay was too small before).

BUG=587074

Review URL: https://codereview.chromium.org/1718233002

Cr-Commit-Position: refs/heads/master@{#376993}
(cherry picked from commit b56bbe4ce3e7276a130a00d83cf00e5672cd6be1)
==========

to

==========
[cherrypick] Fix computation of runtime for throttled tasks

The computation of the delayed task runtime was computing the (virtual)
TimeDomain's now + delay.  That doesn't take into account the skew
between the real time and the virtual time, which meant timers could
run sooner than expected for background tabs.  Timers associated with
foreground tabs are unaffected.

This patch makes the computation of delayed runtime  the responsibility
of the TimeDomain and introduces a ThrottledTimeDomain which computes
the delayed runtime as realtime + delay.

This means timers will no longer run sooner than expected.  Under normal
circumstancs this only timers whose delay modulo 1000ms is less than 100
ms are less likely to be affected.  Timers whose whose delay modulo
1000ms is greater than 900 are highly likely to be affected (there's a
good chance their delay was too small before).

BUG=587074

Review URL: https://codereview.chromium.org/1718233002

Cr-Commit-Position: refs/heads/master@{#376993}
(cherry picked from commit b56bbe4ce3e7276a130a00d83cf00e5672cd6be1)
==========

[alex clarke (OOO till 29th), 2016-02-26 13:54:38]

alexclarke@chromium.org changed reviewers:
+ skyostil@chromium.org

[alex clarke (OOO till 29th), 2016-02-26 13:55:04]

Hi Sami,

I had to do a slightly non-trivial merge on this patch. PTAL.

[alex clarke (OOO till 29th), 2016-02-26 13:55:43]

The CQ bit was checked by alexclarke@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-02-26 13:56:09]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1730153005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1730153005/1

[commit-bot: I haz the power, 2016-02-26 13:56:10]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-02-26 13:56:11]

Dry run: CLs for remote refs other than refs/pending/heads/master must contain
NOTRY=true and NOPRESUBMIT=true in order for the CQ to process them

[Sami, 2016-02-26 15:22:23]

lgtm.

(Note the cq doesn't work for release branches, but we can keep an eye on the
release waterfall after this lands if you're worried about breakage.)

[alex clarke (OOO till 29th), 2016-02-26 15:52:53]

Description was changed from

==========
[cherrypick] Fix computation of runtime for throttled tasks

The computation of the delayed task runtime was computing the (virtual)
TimeDomain's now + delay.  That doesn't take into account the skew
between the real time and the virtual time, which meant timers could
run sooner than expected for background tabs.  Timers associated with
foreground tabs are unaffected.

This patch makes the computation of delayed runtime  the responsibility
of the TimeDomain and introduces a ThrottledTimeDomain which computes
the delayed runtime as realtime + delay.

This means timers will no longer run sooner than expected.  Under normal
circumstancs this only timers whose delay modulo 1000ms is less than 100
ms are less likely to be affected.  Timers whose whose delay modulo
1000ms is greater than 900 are highly likely to be affected (there's a
good chance their delay was too small before).

BUG=587074

Review URL: https://codereview.chromium.org/1718233002

Cr-Commit-Position: refs/heads/master@{#376993}
(cherry picked from commit b56bbe4ce3e7276a130a00d83cf00e5672cd6be1)
==========

to

==========
[cherrypick] Fix computation of runtime for throttled tasks

The computation of the delayed task runtime was computing the (virtual)
TimeDomain's now + delay.  That doesn't take into account the skew
between the real time and the virtual time, which meant timers could
run sooner than expected for background tabs.  Timers associated with
foreground tabs are unaffected.

This patch makes the computation of delayed runtime  the responsibility
of the TimeDomain and introduces a ThrottledTimeDomain which computes
the delayed runtime as realtime + delay.

This means timers will no longer run sooner than expected.  Under normal
circumstancs this only timers whose delay modulo 1000ms is less than 100
ms are less likely to be affected.  Timers whose whose delay modulo
1000ms is greater than 900 are highly likely to be affected (there's a
good chance their delay was too small before).

BUG=587074

Review URL: https://codereview.chromium.org/1718233002

Cr-Commit-Position: refs/heads/master@{#376993}
(cherry picked from commit b56bbe4ce3e7276a130a00d83cf00e5672cd6be1)

R=skyostil@chromium.org

Committed:
https://chromium.googlesource.com/chromium/src/+/fd563254490ae93382cb88a1e9a1...
==========

[alex clarke (OOO till 29th), 2016-02-26 15:52:55]

Committed patchset #2 (id:20001) manually as
fd563254490ae93382cb88a1e9a1c1e54815c97b.

[jaydasika, 2016-02-26 23:33:33]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/1743813002/ by jaydasika@chromium.org.

The reason for reverting is: The reason for reverting is: Speculative revert for
Compile failure on Win, Mac
& Precise 64 Beta Bots (crbug.com/590286) .