Fix value deletion in CleanRegistryEntry.

Registry value names must be expanded before use.

BUG=698997,1059314
R=zmin@chromium.org

Change-Id: I39bc0b31863f46fe2df9e3a873312b865771d3c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2137340
Auto-Submit: Greg Thompson <grt@chromium.org>
Commit-Queue: Owen Min <zmin@chromium.org>
Reviewed-by: Owen Min <zmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756648}

chrome/test/mini_installer/registry_operations.py

@@ -194,6 +194,7 @@ def CleanRegistryEntry(expectation_name, expectation, variable_expander):
       'Invalid expectation for CleanRegistryEntry operation: a \'values\' ' +
       'dictionary is required for optional key %s' % key)
   for value, value_expectation in expectation['values'].iteritems():
+    value = variable_expander.Expand(value)
     assert 'type' not in value_expectation, (
         'Invalid expectation for CleanRegistryEntry operation: value %s\\%s ' +
         'must not specify a \'type\'' % key, value)