Add tracing to ResourceLoadPriorityOptimizer::updateAllImageResourcePriorities

Add tracing to ResourceLoadPriorityOptimizer::updateAllImageResourcePriorities

I discovered while looking into LayoutState's fast
coordinate mapping that we can potentially do a lot
of localToAbsolute calls to determine if images are
onscreen in ResourceLoadPriorityOptimizer. These
calls are out-of-band from the RenderTree walk
done during layout, so don't benefit from the fast-
lookups. That made me believe the function may
actually be expensive.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=176455

[dsinclair, 2014-06-18 18:37:53]

https://codereview.chromium.org/342763002/diff/20001/Source/core/fetch/Resour...
File Source/core/fetch/ResourceLoadPriorityOptimizer.cpp (right):

https://codereview.chromium.org/342763002/diff/20001/Source/core/fetch/Resour...
Source/core/fetch/ResourceLoadPriorityOptimizer.cpp:81: TRACE_EVENT0("webkit",
"ResourceLoadPriorityOptimizer::updateAllImageResourcePriorities");
I've seen some of these as "webkit" and some as "blink" is there a direction on
what we should be using?

[esprehn, 2014-06-18 19:17:06]

lgtm

https://codereview.chromium.org/342763002/diff/20001/Source/core/fetch/Resour...
File Source/core/fetch/ResourceLoadPriorityOptimizer.cpp (right):

https://codereview.chromium.org/342763002/diff/20001/Source/core/fetch/Resour...
Source/core/fetch/ResourceLoadPriorityOptimizer.cpp:81: TRACE_EVENT0("webkit",
"ResourceLoadPriorityOptimizer::updateAllImageResourcePriorities");
Lets use webkit for now, and rename them all to "blink" in one patch.

[leviw_travelin_and_unemployed, 2014-06-18 19:40:04]

The CQ bit was checked by leviw@chromium.org

[commit-bot: I haz the power, 2014-06-18 19:40:34]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/leviw@chromium.org/342763002/20001

[commit-bot: I haz the power, 2014-06-18 21:25:18]

Change committed as 176455