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, 427616
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=188787

[kojii, 2015-01-22 03:44:26]

kojii@chromium.org changed reviewers:
+ hayato@chromium.org

[kojii, 2015-01-22 03:44:26]

PTAL!

[hayato, 2015-01-22 03:48:47]

lgtm

[hayato, 2015-01-22 03:48:51]

The CQ bit was checked by hayato@chromium.org

[commit-bot: I haz the power, 2015-01-22 03:49:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/865753002/1

[commit-bot: I haz the power, 2015-01-22 03:52:40]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=188787

[brucedawson, 2015-01-22 17:35:53]

brucedawson@chromium.org changed reviewers:
+ brucedawson@chromium.org

[brucedawson, 2015-01-22 17:35:54]

lgtm