Skip ParmVarDecl nodes without a name.

BUG=598141

Review-Url: https://codereview.chromium.org/2246263002
Cr-Commit-Position: refs/heads/master@{#414877}
diff --git a/docs/clang_tool_refactoring.md b/docs/clang_tool_refactoring.md
index ef7faabe..89f4b06a 100644
--- a/docs/clang_tool_refactoring.md
+++ b/docs/clang_tool_refactoring.md
@@ -172,7 +172,7 @@
 Synposis:
 
 ```shell
-test_tool.py <tool name>
+tools/clang/scripts/test_tool.py <tool name>
 ```
 
 The name of the tool binary and the subdirectory for the tool in