Split swarm_triggered into 3 builders to make it easier on devs.

scripts/master/factory/chromium_commands.py

Index: scripts/master/factory/chromium_commands.py
diff --git a/scripts/master/factory/chromium_commands.py b/scripts/master/factory/chromium_commands.py
index 8358827f874a5d1c1d1e691a3568d3fe7058fbbe..84549b17c294ef8fa609fb468dabb0dbbe40c881 100644
--- a/scripts/master/factory/chromium_commands.py
+++ b/scripts/master/factory/chromium_commands.py
@@ -1726,7 +1726,7 @@ class ChromiumCommands(commands.FactoryCommands):
     # email, e.g. the blamelist to be properly set, but that causes any patch to
     # be caried over, which is annoying but benign.
     self._factory.addStep(commands.CreateTriggerStep(
-        trigger_name='swarm_triggered',
+        trigger_name=factory_properties['triggered_builder'],
         trigger_set_properties={
             'target_os': self._target_platform,
             'use_swarm_client_revision':