Remove raw base::DictionaryValue::Set in //extensions

extensions/browser/api/web_request/web_request_api_helpers.h

Index: extensions/browser/api/web_request/web_request_api_helpers.h
diff --git a/extensions/browser/api/web_request/web_request_api_helpers.h b/extensions/browser/api/web_request/web_request_api_helpers.h
index d6da9813975969eb66c63557f4092c81e5f8d0a0..5542c88b1d9c88365da50cac2f4e2489733999cc 100644
--- a/extensions/browser/api/web_request/web_request_api_helpers.h
+++ b/extensions/browser/api/web_request/web_request_api_helpers.h
@@ -203,9 +203,8 @@ bool InDecreasingExtensionInstallationTimeOrder(
     const linked_ptr<EventResponseDelta>& a,
     const linked_ptr<EventResponseDelta>& b);
 
-// Converts a string to a list of integers, each in 0..255. Ownership
-// of the created list is passed to the caller.
-base::ListValue* StringToCharList(const std::string& s);
+// Converts a string to a list of integers, each in 0..255.
+std::unique_ptr<base::ListValue> StringToCharList(const std::string& s);
 
 // Converts a list of integer values between 0 and 255 into a string |*out|.
 // Returns true if the conversion was successful.