Fix typo in unit test.
Fix typo in unit test.

BUG=75237
TEST=ui_unittests --gtest_filter=PNGCodec.*
TBR=tony@chromium.org

Review URL: http://codereview.chromium.org/6852003

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@81497 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser