Fix wrong capacity calculation for m_eventPath
Fix wrong capacity calculation for m_eventPath

https://codereview.chromium.org/849783002/
has a bug in the calculation of |reserveCapacity|,
resulting unnecessary realloc, thanks to brucedawson
for pointing this out.

BUG=442632

Review URL: https://codereview.chromium.org/865753002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@188787 bbb929c8-8fbe-4397-9dbb-9b2b20218538

PeterWangIntel/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,kurli/blink-crosswalk,kurli/blink-crosswalk,kurli/blink-crosswalk,PeterWangIntel/blink-crosswalk,PeterWangIntel/blink-crosswalk,kurli/blink-crosswalk,XiaosongWei/blink-crosswalk,smishenk/blink-crosswalk,Pluto-tv/blink-crosswalk,PeterWangIntel/blink-crosswalk,Pluto-tv/blink-crosswalk,Bysmyyr/blink-crosswalk,Bysmyyr/blink-crosswalk,PeterWangIntel/blink-crosswalk,PeterWangIntel/blink-crosswalk,smishenk/blink-crosswalk,smishenk/blink-crosswalk,smishenk/blink-crosswalk,kurli/blink-crosswalk,smishenk/blink-crosswalk,Bysmyyr/blink-crosswalk,kurli/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,PeterWangIntel/blink-crosswalk,Pluto-tv/blink-crosswalk,smishenk/blink-crosswalk,smishenk/blink-crosswalk,XiaosongWei/blink-crosswalk,XiaosongWei/blink-crosswalk,Pluto-tv/blink-crosswalk,Bysmyyr/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,smishenk/blink-crosswalk,kurli/blink-crosswalk,smishenk/blink-crosswalk,XiaosongWei/blink-crosswalk,PeterWangIntel/blink-crosswalk,Bysmyyr/blink-crosswalk,Pluto-tv/blink-crosswalk,XiaosongWei/blink-crosswalk,kurli/blink-crosswalk,smishenk/blink-crosswalk,Bysmyyr/blink-crosswalk,XiaosongWei/blink-crosswalk,kurli/blink-crosswalk,Pluto-tv/blink-crosswalk,PeterWangIntel/blink-crosswalk,XiaosongWei/blink-crosswalk,Bysmyyr/blink-crosswalk,PeterWangIntel/blink-crosswalk,kurli/blink-crosswalk