Add browser tests for extensions tab API.

chrome/browser/extensions/extension_test_api.cc

 // Copyright (c) 2009 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/browser/extensions/extension_test_api.h"
 #include "chrome/common/notification_service.h"
 
 namespace extension_test_api_functions {
 const char kPassFunction[] = "test.notifyPass";
 const char kFailFunction[] = "test.notifyFail";
+const char kLogFunction[] = "test.log";
 };  // namespace extension_test_api_functions
 
 bool ExtensionTestPassFunction::RunImpl() {
   NotificationService::current()->Notify(
       NotificationType::EXTENSION_TEST_PASSED,
       Source<Profile>(dispatcher()->profile()),
       NotificationService::NoDetails());
   return true;
 }
 
 bool ExtensionTestFailFunction::RunImpl() {
   std::string message;
   EXTENSION_FUNCTION_VALIDATE(args_->GetAsString(&message));
   NotificationService::current()->Notify(
       NotificationType::EXTENSION_TEST_FAILED,
       Source<Profile>(dispatcher()->profile()),
       Details<std::string>(&message));
   return true;
 }
+
+bool ExtensionTestLogFunction::RunImpl() {
+  std::string message;
+  EXTENSION_FUNCTION_VALIDATE(args_->GetAsString(&message));
+  printf("%s\n", message.c_str());
+  LOG(INFO) << message;
+  return true;
+}