[cr tool] Re-run activation until the active set is stable.

tools/cr/cr/plugin.py

Index: tools/cr/cr/plugin.py
diff --git a/tools/cr/cr/plugin.py b/tools/cr/cr/plugin.py
index eccd86954aa44abed7249fe8b5677d5b69b78583..824d2c5d8dbeba85d7e5f00eff0b1f046ca3f8b0 100644
--- a/tools/cr/cr/plugin.py
+++ b/tools/cr/cr/plugin.py
@@ -275,13 +275,7 @@ class Plugin(cr.loader.AutoExport):
     Returns:
       the plugin that is currently active.
     """
-    actives = cls.GetAllActive()
-    plugin = cls.Select(context)
-    for active in actives:
-      if active != plugin:
-        active.Deactivate()
-    if plugin and not plugin.is_active:
-      plugin.Activate(context)
+    plugin, _ = _GetActivePlugin(cls, context)
     return plugin
 
   @classproperty
@@ -319,8 +313,26 @@ def ChainModuleConfigs(module):
 cr.loader.scan_hooks.append(ChainModuleConfigs)
 
 
+def _GetActivePlugin(cls, context):
+  activated = False
+  actives = cls.GetAllActive()
+  plugin = cls.Select(context)
+  for active in actives:
+    if active != plugin:
+      active.Deactivate()
+  if plugin and not plugin.is_active:
+    activated = True
+    plugin.Activate(context)
+  return plugin, activated
+
+
 def Activate(context):
   """Activates a plugin for all known plugin types."""
   types = Plugin.Type.__subclasses__()
-  for child in types:
-    child.GetActivePlugin(context)
+  modified = True
+  while modified:
+    modified = False
+    for child in types:
+      _, activated = _GetActivePlugin(child, context)
+      if activated:
+        modified = True