Update fieldtrial_util To Handle Combined Fieldtrial Config Format

tools/variations/fieldtrial_to_struct.py

Index: tools/variations/fieldtrial_to_struct.py
diff --git a/tools/variations/fieldtrial_to_struct.py b/tools/variations/fieldtrial_to_struct.py
index 132f0aa1ca154322f8ac7f7a31a6b687e3e8973d..dec472d7fa04cba6b0210fd05b4e3bfb88fd6888 100755
--- a/tools/variations/fieldtrial_to_struct.py
+++ b/tools/variations/fieldtrial_to_struct.py
@@ -74,11 +74,15 @@ def _GenerateTrials(config, platform):
     if study['experiments']:
       yield study
 
+def ConfigToStudies(config, platform):
+  """Returns the applicable studies from config for the platform."""
+  return [study for study in _GenerateTrials(config, platform)]
+
 def _FieldTrialConfigToDescription(config, platform):
   return {
     'elements': {
       'kFieldTrialConfig': {
-        'studies': [study for study in _GenerateTrials(config, platform)]
+        'studies': ConfigToStudies(config, platform)
       }
     }
   }