Fix "unreachable code" warnings (MSVC warning 4702) in content/.

BUG=346399
TEST=none
R=jam@chromium.org

Review URL: https://codereview.chromium.org/202863004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@258096 0039d316-1c4b-4281-b951-d872f2087c98
19 files changed