Remove more usage of the base::ListValue::Append(Value*) overload.

chrome/test/chromedriver/element_util.h

Index: chrome/test/chromedriver/element_util.h
diff --git a/chrome/test/chromedriver/element_util.h b/chrome/test/chromedriver/element_util.h
index 445ffcdfdf43ae3cf3d439958195eb93c9a4cabe..3131bd13082e475acbb6b05bf3c22db94209b6cc 100644
--- a/chrome/test/chromedriver/element_util.h
+++ b/chrome/test/chromedriver/element_util.h
@@ -20,9 +20,10 @@ struct Session;
 class Status;
 class WebView;
 
-base::DictionaryValue* CreateElement(const std::string& element_id);
+std::unique_ptr<base::DictionaryValue> CreateElement(
+    const std::string& element_id);
 
-base::Value* CreateValueFrom(const WebPoint& point);
+std::unique_ptr<base::DictionaryValue> CreateValueFrom(const WebPoint& point);
 
 // |root_element_id| could be null when no root element is given.
 Status FindElement(int interval_ms,