[Android] Enable root in perf_control.SetHighPerfMode.
[Android] Enable root in perf_control.SetHighPerfMode.

SetHighPerfMode needs root, but it currently only checks to see if
we already have root rather than trying to enable it.

BUG=478104

Review URL: https://codereview.chromium.org/1135393005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#329980}

chuan9/chromium-crosswalk,hgl888/chromium-crosswalk,Chilledheart/chromium,TheTypoMaster/chromium-crosswalk,Just-D/chromium-1,Just-D/chromium-1,TheTypoMaster/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Fireblend/chromium-crosswalk,chuan9/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,chuan9/chromium-crosswalk,Just-D/chromium-1,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Chilledheart/chromium,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,hgl888/chromium-crosswalk,Chilledheart/chromium,PeterWangIntel/chromium-crosswalk,hgl888/chromium-crosswalk,axinging/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Pluto-tv/chromium-crosswalk,chuan9/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Chilledheart/chromium,PeterWangIntel/chromium-crosswalk,Chilledheart/chromium,Just-D/chromium-1,Pluto-tv/chromium-crosswalk,chuan9/chromium-crosswalk,chuan9/chromium-crosswalk,chuan9/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,Just-D/chromium-1,TheTypoMaster/chromium-crosswalk,hgl888/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Fireblend/chromium-crosswalk,hgl888/chromium-crosswalk,Fireblend/chromium-crosswalk,Chilledheart/chromium,hgl888/chromium-crosswalk,Just-D/chromium-1,TheTypoMaster/chromium-crosswalk,Fireblend/chromium-crosswalk,Just-D/chromium-1,Pluto-tv/chromium-crosswalk,Just-D/chromium-1,Fireblend/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Chilledheart/chromium,chuan9/chromium-crosswalk,Chilledheart/chromium,hgl888/chromium-crosswalk,Chilledheart/chromium,axinging/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Pluto-tv/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,hgl888/chromium-crosswalk,hgl888/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Fireblend/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Fireblend/chromium-crosswalk,Just-D/chromium-1,chuan9/chromium-crosswalk,Fireblend/chromium-crosswalk,Fireblend/chromium-crosswalk,Pluto-tv/chromium-crosswalk