Modify the RenderThread to track the number of widgets...

Modify the RenderThread to track the number of widgets
and "hidden widgets" which are running through that thread.

By knowing the if the widgets are all hidden, the thread
can accurately inform V8 when it is idle so that V8 can 
better cleanup unused memory when idle.

BUG=none
TEST=none


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=24227

[darin (slow to review), 2009-08-22 14:57:05]

Looks good, but I'm not so sure about running a repeating 1 sec timer in each
renderer all the time.

[Mike Belshe, 2009-08-22 17:11:17]

On 2009/08/22 14:57:05, darin wrote:
> Looks good, but I'm not so sure about running a repeating 1 sec timer in each
> renderer all the time.

OK.  I could either reduce the frequency (simplest), or I could put in more code
to only run the timer when all widgets are in the background, and I could even
have it stop after some amount of time.  This  is more code compexity, but it
would make the timers stop.

[darin (slow to review), 2009-08-22 18:58:11]

On 2009/08/22 17:11:17, Mike Belshe wrote:
> On 2009/08/22 14:57:05, darin wrote:
> > Looks good, but I'm not so sure about running a repeating 1 sec timer in
each
> > renderer all the time.
> 
> OK.  I could either reduce the frequency (simplest), or I could put in more
code
> to only run the timer when all widgets are in the background, and I could even
> have it stop after some amount of time.  This  is more code compexity, but it
> would make the timers stop.

How about if we only run the timer when the widgets are in the background. 
Then, start the timer with a short interval, and continue the timer with a long
interval.  That should be fairly simple too.

[Mike Belshe, 2009-08-23 16:51:24]

OK - done.

On 2009/08/22 18:58:11, darin wrote:
> On 2009/08/22 17:11:17, Mike Belshe wrote:
> > On 2009/08/22 14:57:05, darin wrote:
> > > Looks good, but I'm not so sure about running a repeating 1 sec timer in
> each
> > > renderer all the time.
> > 
> > OK.  I could either reduce the frequency (simplest), or I could put in more
> code
> > to only run the timer when all widgets are in the background, and I could
even
> > have it stop after some amount of time.  This  is more code compexity, but
it
> > would make the timers stop.
> 
> How about if we only run the timer when the widgets are in the background. 
> Then, start the timer with a short interval, and continue the timer with a
long
> interval.  That should be fairly simple too.

[darin (slow to review), 2009-08-23 19:00:17]

Very nice!  LGTM