[chromedriver] Implement commands: findChildElement, findChildElements.

chrome/test/chromedriver/commands.h

Index: chrome/test/chromedriver/commands.h
diff --git a/chrome/test/chromedriver/commands.h b/chrome/test/chromedriver/commands.h
index 3d19841620b731ab78706c7b65404d8e1d6a1080..4f2fa6e5768d5725367542d7d4f24744fc8c7f79 100644
--- a/chrome/test/chromedriver/commands.h
+++ b/chrome/test/chromedriver/commands.h
@@ -72,12 +72,28 @@ Status ExecuteGetTitle(
 
 // Search for an element on the page, starting from the document root.
 Status ExecuteFindElement(
+    int interval_ms,
     Session* session,
     const base::DictionaryValue& params,
     scoped_ptr<base::Value>* value);
 
 // Search for multiple elements on the page, starting from the document root.
 Status ExecuteFindElements(
+    int interval_ms,
+    Session* session,
+    const base::DictionaryValue& params,
+    scoped_ptr<base::Value>* value);
+
+// Search for an element on the page, starting from the given element.
+Status ExecuteFindChildElement(
+    int interval_ms,
+    Session* session,
+    const base::DictionaryValue& params,
+    scoped_ptr<base::Value>* value);
+
+// Search for multiple elements on the page, starting from the given element.
+Status ExecuteFindChildElements(
+    int interval_ms,
     Session* session,
     const base::DictionaryValue& params,
     scoped_ptr<base::Value>* value);