Fixed edgecase bugs for WebMediaPlayer buffered()
Fixed edgecase bugs for WebMediaPlayer buffered()

Fixed some bugs with buffered() in WebMediaPlayer regarding edge cases:
making sure buffered_ is always initialized before trying to write, and
making sure buffered_.end is never after buffered_.start.

Review URL: http://codereview.chromium.org/2691005

git-svn-id: http://src.chromium.org/svn/trunk/src@49621 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: c87536ff2b19315185df52c3b4ebab46f0e60d43
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