If you create a patch which can be applied on all of your master's builders, you can modify your Buildbot master so the patch is applied (as in the TryMaster configuration).
1. Ensure your patch is relative to src. The following command should 'just work':
2. Place the patch at /tmp/patch (this path should be readable by your Buildbot master).
3. Modify ./scripts/master/chromium_step.py with the following patch:
4. Restart your master. When each builder begins again, your patch should be sent to the builders and applied locally just like a normal try job's patch.