Revert of Revert of Revert 221427 "Add instrumentation to the MessagePumpMac family ..."

Revert of Revert of Revert 221427 "Add instrumentation to the MessagePumpMac family ..." (https://codereview.chromium.org/366873002/)

Reason for revert:
Trying again. Will clobber builder since I can't repro this.

Original issue's description:
> Revert of Revert 221427 "Add instrumentation to the MessagePumpMac family ..." (https://codereview.chromium.org/360373004/)
> 
> Reason for revert:
> This revert seems to cause build failure:
> 
> http://build.chromium.org/p/chromium.memory/builders/Linux%20ASan%20LSan%20Builder/builds/8982
> http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Full/builds/6497
> http://build.chromium.org/p/chromium.linux/builders/Linux%20Builder/builds/34221
> 
> 
> Original issue's description:
> > Revert 221427 "Add instrumentation to the MessagePumpMac family ..."
> > 
> > This code is no longer needed, since the experiment is not viable.
> > 
> > > Add instrumentation to the MessagePumpMac family of classes.
> > >
> > > This adds UMA-uploaded histograms of sampling intervals for key points of data:
> > > * Total time spent in a CFRunLoop
> > > * Total time waiting in CFRunLoop
> > > * Total time servicing MessagePump::Delegate (the MessageLoop)
> > > * The MessageLoop queue size and queueing delay before servicing
> > >
> > > It adds 1 second sampling for 15 seconds at startup, only for the main thread
> > > (NSApplication-based) run loops.
> > >
> > > The data will be used to determine if adding scheduling-like behavior to the
> > > MessagePump will result in more efficient processing of the MessageLoop work.
> > >
> > > An unforunate side effect of this change is exposing another method on the
> > > MessagePump::Delegate interface, but there does not appear to be a better way
> > > to do this.
> > >
> > > BUG=264886
> > > R=jar@chromium.org, mark@chromium.org
> > >
> > > Review URL: https://codereview.chromium.org/22911026
> > 
> > TBR=rsesek@chromium.org
> > 
> > Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=280939
> 
> TBR=rsesek@chromium.org,rsesek@chromium.org
> NOTREECHECKS=true
> NOTRY=true
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=280948

TBR=rsesek@chromium.org,tzik@chromium.org
NOTREECHECKS=true
NOTRY=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=281050

[Robert Sesek, 2014-07-02 16:37:47]

Created Revert of Revert of Revert 221427 "Add instrumentation to the
MessagePumpMac family ..."

[commit-bot: I haz the power, 2014-07-02 16:38:17]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/rsesek@chromium.org/368893002/1

[commit-bot: I haz the power, 2014-07-02 16:39:37]

Change committed as 281050