Another batrch of performance improvements for NNTP...

Another batch of performance improvements for NNTP.

Hard code the DOM and the layout for the default case so that we do not
need to do any js layout at startup.

Be more careful when calling layout. I added a dirty bit so that we
don't layout too often.

CSS cleanup/optimization to make selectors faster.

TEST=Run the perf test

BUG=13362
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=19877

[Miranda Callahan, 2009-07-02 19:59:24]

LGTM, but should wait for Glen, for his Javascript expertise.

On 2009/07/02 19:13:01, arv wrote:
>

[arv (Not doing code reviews), 2009-07-02 20:40:16]

Here are the results from running NewTabUIStartupTest.PerfCold

*RESULT new_tab: tab_cold= [244.00,223.00,231.00,228.00,205.00,] ms
*RESULT new_tab: tab_cold= [242.00,235.00,225.00,229.00,251.00,] ms
*RESULT new_tab: tab_cold= [284.00,227.00,442.00,221.00,434.00,] ms

and the old NTP for reference:

*RESULT new_tab: tab_cold= [1103.00,777.00,761.00,887.00,888.00,] ms
*RESULT new_tab: tab_cold= [954.00,793.00,735.00,927.00,895.00,] ms
*RESULT new_tab: tab_cold= [983.00,906.00,884.00,815.00,1157.00,] ms

The lousy results for the old NTP is due to the first-run overlay which shows up
late due to it coming in with the template data.

[Glen Murphy, 2009-07-02 22:40:25]

LGTM