Fix a bug that could occur when converting strings with leading characters above 127.

BUG=None
TEST=base_unittests --gtest_filter=*StringToInt*

Review URL: http://codereview.chromium.org/4129012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@64789 0039d316-1c4b-4281-b951-d872f2087c98
2 files changed