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

scripts/master/factory/swarm_factory.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Utility class to build the Swarm master BuildFactory's.
 
 Based on chromium_factory.py and adds chromium-on-swarm-specific steps.
 
 Common usage:
 - For a split builder&tester configuration, use:
   - One ChromiumFactory() builder with 'run_default_swarm_tests' set to the list
     of tests to run on Swarm on the 'tester'.
-  - One SwarmTestBuilder() builder named 'swarm_triggered', the builder name
-    is currently hardcoded.
+  - One SwarmTestBuilder() builder named something like 'linux_swarm_triggered'.
+    It is defined as fp['triggered_builder']
 
 - For a single buildertester configuration, use:
   - SwarmFactory()
 """
 
 from master.factory import build_factory
 from master.factory import chromium_factory
 from master.factory import swarm_commands
 
 
@@ skipping 146 matching lines @@
 
     # Reorder the tests by the order specified in SWARM_TESTS. E.g. the slower
     # tests are retrieved last.
     for swarm_test in SWARM_TESTS:
       if swarm_test.test_name in tests:
         tests.remove(swarm_test.test_name)
         swarm_command_obj.AddIsolateTest(swarm_test.test_name)
 
     assert not tests
     return f