Fix gyp compile failures caused by moving broadcastchannel code.

I don't understand how gyp works with mojo bindings, but this seems to
fix some compile failures introduced in https://codereview.chromium.org/2158913006

BUG=630666

Review-Url: https://codereview.chromium.org/2173883003
Cr-Commit-Position: refs/heads/master@{#407286}
1 file changed