[ChromeDriver] Select the main frame if a non-existant child frame is targeted.

chrome/test/chromedriver/devtools_client_impl.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/devtools_client_impl.h"
 
 #include "base/bind.h"
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "base/logging.h"
@@ skipping 142 matching lines @@
   if (!parser_func_.Run(message, expected_id, type, event, response))
     return Status(kUnknownError, "bad inspector message: " + message);
   if (*type == internal::kEventMessageType)
     return NotifyEventListeners(event->method, *event->params);
   if (*type == internal::kCommandResponseMessageType) {
     if (cmd_response_map_.count(response->id) == 0) {
       return Status(kUnknownError, "unexpected command message");
     } else if (response->result) {
       cmd_response_map_[response->id] = response->result.release();
     } else {
+      scoped_ptr<base::Value> error(base::JSONReader::Read(response->error));
+      base::DictionaryValue* error_dict;
+      if (!error || !error->GetAsDictionary(&error_dict))
+        return Status(kUnknownError, "inspector error with no error code");
+      int error_code;
+      if (error_dict->GetInteger("code", &error_code) &&
+          error_code == internal::kContextIdNotFound) {
+        cmd_response_map_.erase(response->id);
+        return Status(kNoSuchFrame);
+      }
       return Status(kUnknownError, "inspector error: " + response->error);
     }
   }
   return Status(kOk);
 }
 
 Status DevToolsClientImpl::NotifyEventListeners(
     const std::string& method,
     const base::DictionaryValue& params) {
   for (std::list<DevToolsEventListener*>::iterator iter = listeners_.begin();
@@ skipping 47 matching lines @@
     if (unscoped_result)
       command_response->result.reset(unscoped_result->DeepCopy());
     else
       base::JSONWriter::Write(unscoped_error, &command_response->error);
     return true;
   }
   return false;
 }
 
 }  // namespace internal