Add virtual destructor to base class to resolve leak.
Add virtual destructor to base class to resolve leak.

This appears to resolve the regression that might have
been instigated in 44435.

This was very significant on Windows, as the derived
class held a lot of data in file_version_info_win.cc.

BUG=44320
r=mbelshe
Review URL: http://codereview.chromium.org/2131023

git-svn-id: http://src.chromium.org/svn/trunk/src@47964 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 1c877eb0e33c9a5c983bd9ff1046ae1a7b2d054e
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser