Update floating builder logic, add to "chromiumos"

scripts/common/slave_alloc.py

 # Copyright 2015 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.
 
 """Library to generate, maintain, and read static slave pool maps."""
 
 import collections
 import itertools
 import json
 import os
@@ skipping 138 matching lines @@
     """Saves the current slave pool set to the store path."""
     state_dict = {}
     if self._state and self._state.class_map:
       class_map = state_dict['class_map'] = {}
       for sc, slave_list in self._state.class_map.iteritems():
         class_dict = class_map.setdefault(sc.name, {})
         subtype_dict = class_dict.setdefault(sc.subtype, [])
         subtype_dict.extend(slave_list)
 
     if self._list_unallocated:
-      state_dict['unallocated'] = list(self._state.unallocated or ())
+      state_dict['unallocated'] = sorted(list(self._state.unallocated or ()))
 
     with open(self.state_path, 'w') as fd:
       json.dump(state_dict, fd, sort_keys=True, indent=2)
 
   def AddPool(self, name, *slaves):
     """Returns (str): The slave pool that was allocated (for chaining).
 
     Args:
       name (str): The slave pool name.
       slaves: Slave name strings that belong to this pool.
@@ skipping 169 matching lines @@
 
     # Convert SlaveMapEntry fields to immutable form.
     result = SlaveMap(
         entries={},
         unallocated=frozenset(n_state.unallocated))
     for k, v in slave_map_entries.iteritems():
       result.entries[k] = SlaveMapEntry(
           classes=frozenset(v.classes),
           keys=tuple(sorted(v.keys)))
     return result
+
+
+def BuildClassMap(sm):
+  class_map = {}
+  for s, e in sm.entries.iteritems():
+    for cls in e.classes:
+      subtype_map = class_map.setdefault(cls.name, {})
+      subtype_map.setdefault(cls.subtype, set()).add(s)
+  return class_map