Prerender only the selected page in the app list.
Prerender only the selected page in the app list.

On Windows, a warmup task is scheduled 60 seconds after Chrome startup
to improve app launcher show times. Part of this task is to cache text
labels on the app list.

This CL reduces the number of pages pre-rendered from (up to) 3 to just
1; the selected page. This is unlikely to have a big impact, since the
slowest parts of text layout are still touched, to layout items before
the prerender step. This CL is to verify that claim.

BUG=440224

Review URL: https://codereview.chromium.org/821113002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#309895}

hgl888/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,M4sse/chromium.src,ltilve/chromium,dushu1203/chromium.src,Just-D/chromium-1,jaruba/chromium.src,Chilledheart/chromium,axinging/chromium-crosswalk,ltilve/chromium,Jonekee/chromium.src,Jonekee/chromium.src,markYoungH/chromium.src,krieger-od/nwjs_chromium.src,M4sse/chromium.src,dushu1203/chromium.src,dushu1203/chromium.src,krieger-od/nwjs_chromium.src,Jonekee/chromium.src,TheTypoMaster/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,hgl888/chromium-crosswalk,krieger-od/nwjs_chromium.src,TheTypoMaster/chromium-crosswalk,ltilve/chromium,Just-D/chromium-1,Jonekee/chromium.src,hgl888/chromium-crosswalk,chuan9/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,markYoungH/chromium.src,PeterWangIntel/chromium-crosswalk,mohamed--abdel-maksoud/chromium.src,Chilledheart/chromium,fujunwei/chromium-crosswalk,chuan9/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Chilledheart/chromium,dushu1203/chromium.src,mohamed--abdel-maksoud/chromium.src,jaruba/chromium.src,chuan9/chromium-crosswalk,Just-D/chromium-1,M4sse/chromium.src,mohamed--abdel-maksoud/chromium.src,markYoungH/chromium.src,fujunwei/chromium-crosswalk,krieger-od/nwjs_chromium.src,Fireblend/chromium-crosswalk,krieger-od/nwjs_chromium.src,chuan9/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,axinging/chromium-crosswalk,krieger-od/nwjs_chromium.src,Pluto-tv/chromium-crosswalk,dednal/chromium.src,Just-D/chromium-1,jaruba/chromium.src,markYoungH/chromium.src,chuan9/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,chuan9/chromium-crosswalk,Pluto-tv/chromium-crosswalk,M4sse/chromium.src,PeterWangIntel/chromium-crosswalk,hgl888/chromium-crosswalk,dednal/chromium.src,dednal/chromium.src,Chilledheart/chromium,fujunwei/chromium-crosswalk,ltilve/chromium,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,markYoungH/chromium.src,PeterWangIntel/chromium-crosswalk,jaruba/chromium.src,mohamed--abdel-maksoud/chromium.src,TheTypoMaster/chromium-crosswalk,markYoungH/chromium.src,jaruba/chromium.src,axinging/chromium-crosswalk,fujunwei/chromium-crosswalk,Just-D/chromium-1,ltilve/chromium,dushu1203/chromium.src,mohamed--abdel-maksoud/chromium.src,M4sse/chromium.src,PeterWangIntel/chromium-crosswalk,Fireblend/chromium-crosswalk,dednal/chromium.src,krieger-od/nwjs_chromium.src,fujunwei/chromium-crosswalk,dushu1203/chromium.src,M4sse/chromium.src,Jonekee/chromium.src,dushu1203/chromium.src,mohamed--abdel-maksoud/chromium.src,mohamed--abdel-maksoud/chromium.src,hgl888/chromium-crosswalk,Just-D/chromium-1,ltilve/chromium,hgl888/chromium-crosswalk,dushu1203/chromium.src,Just-D/chromium-1,krieger-od/nwjs_chromium.src,dushu1203/chromium.src,jaruba/chromium.src,dednal/chromium.src,Jonekee/chromium.src,PeterWangIntel/chromium-crosswalk,chuan9/chromium-crosswalk,Fireblend/chromium-crosswalk,fujunwei/chromium-crosswalk,jaruba/chromium.src,dednal/chromium.src,markYoungH/chromium.src,Pluto-tv/chromium-crosswalk,krieger-od/nwjs_chromium.src,axinging/chromium-crosswalk,Chilledheart/chromium,chuan9/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Fireblend/chromium-crosswalk,Fireblend/chromium-crosswalk,axinging/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,chuan9/chromium-crosswalk,markYoungH/chromium.src,ltilve/chromium,ltilve/chromium,Fireblend/chromium-crosswalk,krieger-od/nwjs_chromium.src,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,M4sse/chromium.src,dednal/chromium.src,dushu1203/chromium.src,mohamed--abdel-maksoud/chromium.src,Pluto-tv/chromium-crosswalk,hgl888/chromium-crosswalk,markYoungH/chromium.src,markYoungH/chromium.src,dednal/chromium.src,PeterWangIntel/chromium-crosswalk,M4sse/chromium.src,hgl888/chromium-crosswalk,dushu1203/chromium.src,Fireblend/chromium-crosswalk,mohamed--abdel-maksoud/chromium.src,Chilledheart/chromium,Fireblend/chromium-crosswalk,M4sse/chromium.src,ltilve/chromium,jaruba/chromium.src,Pluto-tv/chromium-crosswalk,fujunwei/chromium-crosswalk,axinging/chromium-crosswalk,Chilledheart/chromium,hgl888/chromium-crosswalk,Jonekee/chromium.src,markYoungH/chromium.src,Just-D/chromium-1,mohamed--abdel-maksoud/chromium.src,TheTypoMaster/chromium-crosswalk,dednal/chromium.src,Fireblend/chromium-crosswalk,axinging/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Jonekee/chromium.src,Jonekee/chromium.src,jaruba/chromium.src,M4sse/chromium.src,Jonekee/chromium.src,fujunwei/chromium-crosswalk,M4sse/chromium.src,Pluto-tv/chromium-crosswalk,dednal/chromium.src,fujunwei/chromium-crosswalk,jaruba/chromium.src,mohamed--abdel-maksoud/chromium.src,krieger-od/nwjs_chromium.src,Jonekee/chromium.src,Chilledheart/chromium,Just-D/chromium-1,dednal/chromium.src,jaruba/chromium.src