Disable extension startup tests on Mac, since they're causing it to hang.

chrome/test/startup/startup_test.cc

 // Copyright (c) 2006-2008 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 "base/file_util.h"
 #include "base/path_service.h"
 #include "base/platform_thread.h"
 #include "base/string_util.h"
 #include "base/test_file_util.h"
 #include "base/time.h"
@@ skipping 142 matching lines @@
                  true /* important */, UITest::DEFAULT_THEME);
 }
 
 // TODO(mpcomplete): Should we have reference timings for all these?
 
 TEST_F(StartupTest, PerfCold) {
   RunStartupTest("cold", "t", true /* cold */, false /* not important */,
                  UITest::DEFAULT_THEME);
 }
 
+#if defined(OS_MACOSX)
+// TODO(mpcomplete): running these tests on a mac builder results in leaked
+// chrome processes, causing the build slave to hang.
+// http://code.google.com/p/chromium/issues/detail?id=22287
+#else
 TEST_F(StartupTest, PerfExtensionEmpty) {
   SetUpWithFileURL();
   SetUpWithExtensionsProfile("empty");
   RunStartupTest("warm", "t", false /* cold */, false /* not important */,
                  UITest::DEFAULT_THEME);
 }
 
 TEST_F(StartupTest, PerfExtensionToolstrips1) {
   SetUpWithFileURL();
   SetUpWithExtensionsProfile("toolstrips1");
@@ skipping 18 matching lines @@
                  UITest::DEFAULT_THEME);
 }
 
 TEST_F(StartupTest, PerfExtensionContentScript50) {
   SetUpWithFileURL();
   SetUpWithExtensionsProfile("content_scripts50");
   RunStartupTest("warm", "extension_content_scripts50",
                  false /* cold */, false /* not important */,
                  UITest::DEFAULT_THEME);
 }
-
+#endif
 
 #if defined(OS_WIN)
 // TODO(port): Enable gears tests on linux/mac once gears is working.
 TEST_F(StartupTest, PerfGears) {
   SetUpWithFileURL();
   RunStartupTest("warm", "gears", false /* not cold */,
                  false /* not important */, UITest::DEFAULT_THEME);
 }
 
 TEST_F(StartupTest, PerfColdGears) {
@@ skipping 19 matching lines @@
                  false /* not important */, UITest::CUSTOM_FRAME);
 }
 
 TEST_F(StartupTest, PerfColdNativeFrameGtkTheme) {
   RunStartupTest("warm", "custom-frame-gtk-theme", false /* warm */,
                  false /* not important */, UITest::CUSTOM_FRAME_NATIVE_THEME);
 }
 #endif
 
 }  // namespace