[ChromeDriver] Added CommandListener interface

chrome/test/chromedriver/commands.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/test/chromedriver/commands.h"
 
 #include <algorithm>
 #include <list>
 #include <utility>
 
@@ skipping 133 matching lines @@
                    Status(return_ok_without_session ? kOk : kNoSuchSession),
                    base::Passed(scoped_ptr<base::Value>()),
                    std::string()));
     return;
   }
 
   if (IsVLogOn(0)) {
     VLOG(0) << "COMMAND " << command_name << " "
             << FormatValueForDisplay(*params);
   }
+
+  Status status = session->OnCommand(std::string(command_name));

[klm, 2014/06/16 16:11:29]

I am concerned that this is only done on session commands -- from under
ExecuteSessionCommand, but not from Execute{Window,Element,Alert}Command, unless
those go through ExecuteSessionCommand, which I don't see that they would,
although then I'm not sure how the window/element/alert commands end up running
on the session thread... See http_handler.cc for the top level command dispatch
logic.

The listener should get invoked on all commands, not just session, and then it's
up to the listener implementation to decide what to do on what commands.

[johnmoore, 2014/06/16 17:28:34]

I believe that the window and element commands do go through
ExecuteSessionCommand due to overloading of HttpHandler::WrapToCommand. I
checked to make sure OnCommand would be triggered for "Navigate" (window
command) and "FindElement" (element command). I have now confirmed the same for
"GetAlertMessage" (alert command); it is triggered as well.

+
+  if (status.IsError())
+    LOG(ERROR) << "Error when notifying listeners of command";
+
   scoped_ptr<base::Value> value;
-  Status status = command.Run(session, *params, &value);
+  status = command.Run(session, *params, &value);
 
   if (status.IsError() && session->chrome) {
     if (!session->quit && session->chrome->HasCrashedWebView()) {
       session->quit = true;
       std::string message("session deleted because of page crash");
       if (!session->detach) {
         Status quit_status = session->chrome->Quit();
         if (quit_status.IsError())
           message += ", but failed to kill browser:" + quit_status.message();
       }
@@ skipping 77 matching lines @@
   }
 }
 
 namespace internal {
 
 void CreateSessionOnSessionThreadForTesting(const std::string& id) {
   SetThreadLocalSession(make_scoped_ptr(new Session(id)));
 }
 
 }  // namespace internal