chassis: Kill duplicate extension-enabled tracking

DeviceExtension struct had two duplicate mechanisms for tracking
enabled device extensions. Removed the less useful one.

Change-Id: I57e824d2342fe4a9504bf44b75e58c0905044442
diff --git a/scripts/helper_file_generator.py b/scripts/helper_file_generator.py
index 759bf1b..ef3810d 100644
--- a/scripts/helper_file_generator.py
+++ b/scripts/helper_file_generator.py
@@ -526,6 +526,7 @@
             '#include <unordered_map>',
             '#include <utility>',
             '#include <set>',
+            '#include <vector>',
             '',
             '#include <vulkan/vulkan.h>',
             '']
@@ -564,12 +565,6 @@
             struct  = [struct_decl]
             struct.extend([ '    bool %s{false};' % field_name[ext_name] for ext_name, info in extension_items])
 
-            # Create struct entries for saving extension count and extension list from Instance, DeviceCreateInfo
-            if type == 'Instance':
-                struct.extend([
-                    '',
-                    '    std::unordered_set<std::string> device_extension_set;'])
-
             # Construct the extension information map -- mapping name to data member (field), and required extensions
             # The map is contained within a static function member for portability reasons.
             info_type = '%sInfo' % type
@@ -635,11 +630,6 @@
                     '        *this = %s(*instance_extensions);' % struct_type,
                     '']),
             struct.extend([
-                    '',
-                    '        // Save pCreateInfo device extension list',
-                    '        for (uint32_t extn = 0; extn < pCreateInfo->enabledExtensionCount; extn++) {',
-                    '           device_extension_set.insert(pCreateInfo->ppEnabledExtensionNames[extn]);',
-                    '        }',
                 '',
                 '        static const std::vector<const char *> V_1_0_promoted_%s_extensions = {' % type.lower() ])
             struct.extend(['            %s_EXTENSION_NAME,' % ext_name.upper() for ext_name in promoted_ext_list])