ChromeDriver should be able to focus on a frame using its frame element,

chrome/test/webdriver/dispatch.cc

Index: chrome/test/webdriver/dispatch.cc
===================================================================
--- chrome/test/webdriver/dispatch.cc	(revision 79141)
+++ chrome/test/webdriver/dispatch.cc	(working copy)
@@ -59,6 +59,15 @@
   shutdown_event->Signal();
 }
 
+void SendNoContentResponse(struct mg_connection* connection,
+                           const struct mg_request_info* request_info,
+                           void* user_data) {
+  std::string response = "HTTP/1.1 204 No Content\r\n"
+                         "Content-Length:0\r\n"
+                         "\r\n";
+  mg_write(connection, response.data(), response.length());
+}
+
 void SendNotImplementedError(struct mg_connection* connection,
                              const struct mg_request_info* request_info,
                              void* user_data) {
@@ -245,7 +254,11 @@
 }  // namespace internal
 
 Dispatcher::Dispatcher(struct mg_context* context, const std::string& root)
-    : context_(context), root_(root) {}
+    : context_(context), root_(root) {
+  // Overwrite mongoose's default handler for /favicon.ico to always return a
+  // 204 response so we don't spam the logs with 404s.
+  mg_set_uri_callback(context_, "/favicon.ico", &SendNoContentResponse, NULL);
+}
 
 Dispatcher::~Dispatcher() {}