Vulkan: Fix build after roll.

Remove struct_size_helper from LVL build. This was causing
significant problems on the Chromium CQ.

Also fix the warning of duplicate definitions in reg.py by
staging scripts to a temporary folder so we can use a fixed
version.

Bug: angleproject:2482
Bug: chromium:833736
Change-Id: Ide7202fe14bf6c83419f19bc07113df23d51807a
Reviewed-on: https://chromium-review.googlesource.com/1014902
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>

third_party/vulkan-validation-layers/BUILD.gn

@@ -66,16 +66,6 @@ helper_script_and_deps = [
     "vk_safe_struct.h",
     "helper_file_generator.py",
   ],
-  [
-    "vulkan_gen_struct_size_helper_c",
-    "vk_struct_size_helper.c",
-    "helper_file_generator.py",
-  ],
-  [
-    "vulkan_gen_struct_size_helper_h",
-    "vk_struct_size_helper.h",
-    "helper_file_generator.py",
-  ],
   [
     "vulkan_gen_thread_check_helper",
     "thread_check.h",
@@ -113,16 +103,49 @@ helper_script_and_deps = [
   ],
 ]
 
+# Stage all scripts to the temporary gen directory so we can override 'reg.py'.
+# TODO(tobine): Remove workaround when fix upstreamed. http://anglebug.com/2482
+copy("vulkan_script_workaround") {
+  sources = [
+    "reg.py",
+    "src/layers/vk_validation_error_messages.h",
+    "src/scripts/cgenerator.py",
+    "src/scripts/common_codegen.py",
+    "src/scripts/dispatch_table_helper_generator.py",
+    "src/scripts/generator.py",
+    "src/scripts/helper_file_generator.py",
+    "src/scripts/loader_extension_generator.py",
+    "src/scripts/lvl_genvk.py",
+    "src/scripts/mock_icd_generator.py",
+    "src/scripts/object_tracker_generator.py",
+    "src/scripts/parameter_validation_generator.py",
+    "src/scripts/threading_generator.py",
+    "src/scripts/unique_objects_generator.py",
+    "src/scripts/vk.xml",
+    "src/scripts/vuid_mapping.py",
+  ]
+  outputs = [
+    "$vulkan_gen_dir/{{source_file_part}}",
+  ]
+}
+
 foreach(script_and_dep, helper_script_and_deps) {
   target_name = script_and_dep[0]
   file = script_and_dep[1]
   dep = script_and_dep[2]
   target("action", target_name) {
-    script = "src/scripts/lvl_genvk.py"
+    deps = [
+      ":vulkan_script_workaround",
+    ]
+    script = "$vulkan_gen_dir/lvl_genvk.py"
     inputs = [
-      "src/scripts/$dep",
-      "src/scripts/generator.py",
-      "src/scripts/reg.py",
+      "$vulkan_gen_dir/$dep",
+      "$vulkan_gen_dir/cgenerator.py",
+      "$vulkan_gen_dir/common_codegen.py",
+      "$vulkan_gen_dir/generator.py",
+      "$vulkan_gen_dir/reg.py",
+      "$vulkan_gen_dir/vuid_mapping.py",
+      "$vulkan_gen_dir/vk_validation_error_messages.h",
       "src/scripts/vk.xml",
     ]
     outputs = [