content/public/common should depend on the mojo_bindings target

Rather than the mojo_bindings_mojom target, which exports sources, and
causes multiple definition errors in component builds.

Followup to https://codereview.chromium.org/2089823002

BUG=622076
TBR=jam@chromium.org,rockot@chromium.org

Review-Url: https://codereview.chromium.org/2088163002
Cr-Commit-Position: refs/heads/master@{#401230}
1 file changed