The test is only failing on Mac, so lets just disabled it for Mac specificall...

chrome/browser/extensions/extension_updater_unittest.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 <map>
 
 #include "base/file_util.h"
 #include "base/rand_util.h"
 #include "base/stl_util-inl.h"
 #include "base/string_util.h"
 #include "base/thread.h"
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/browser/extensions/extension_updater.h"
 #include "chrome/browser/extensions/extensions_service.h"
 #include "chrome/browser/net/test_url_fetcher_factory.h"
 #include "chrome/common/extensions/extension.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/extensions/extension_error_reporter.h"
 #include "chrome/common/pref_names.h"
 #include "chrome/common/pref_service.h"
 #include "net/base/escape.h"
 #include "net/base/load_flags.h"
 #include "net/url_request/url_request_status.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "libxml/globals.h"
 
+#if defined(OS_MACOSX)
+// These tests crash frequently on Mac 10.5 Tests debug. http://crbug.com/26035.
+#define MAYBE_TestBlacklistDownloading DISABLED_TestBlacklistDownloading
+#define MAYBE_TestBlacklistUpdateCheckRequests DISABLED_TestBlacklistUpdateCheckRequests
+#else
+#define MAYBE_TestBlacklistDownloading TestBlacklistDownloading
+#define MAYBE_TestBlacklistUpdateCheckRequests TestBlacklistUpdateCheckRequests
+#endif
+
 static int expected_load_flags =
     net::LOAD_DO_NOT_SEND_COOKIES | net::LOAD_DO_NOT_SAVE_COOKIES;
 
 // Do-nothing base class for further specialized test classes.
 class MockService : public ExtensionUpdateService {
  public:
   MockService() {}
   virtual ~MockService() {}
 
   virtual const ExtensionList* extensions() const {
@@ skipping 544 matching lines @@
 };
 
 // Because we test some private methods of ExtensionUpdater, it's easer for the
 // actual test code to live in ExtenionUpdaterTest methods instead of TEST_F
 // subclasses where friendship with ExtenionUpdater is not inherited.
 
 TEST(ExtensionUpdaterTest, TestExtensionUpdateCheckRequests) {
   ExtensionUpdaterTest::TestExtensionUpdateCheckRequests();
 }
 
-// This test is disabled, see bug 26035
-TEST(ExtensionUpdaterTest, DISABLED_TestBlacklistUpdateCheckRequests) {
+// This test is disabled on Mac, see http://crbug.com/26035.
+TEST(ExtensionUpdaterTest, MAYBE_TestBlacklistUpdateCheckRequests) {
   ExtensionUpdaterTest::TestBlacklistUpdateCheckRequests();
 }
 
 TEST(ExtensionUpdaterTest, TestDetermineUpdates) {
   ExtensionUpdaterTest::TestDetermineUpdates();
 }
 
 TEST(ExtensionUpdaterTest, TestMultipleManifestDownloading) {
   ExtensionUpdaterTest::TestMultipleManifestDownloading();
 }
 
 TEST(ExtensionUpdaterTest, TestSingleExtensionDownloading) {
   ExtensionUpdaterTest::TestSingleExtensionDownloading();
 }
 
-// This test is disabled, see bug 26035
-TEST(ExtensionUpdaterTest, DISABLED_TestBlacklistDownloading) {
+// This test is disabled on Mac, see http://crbug.com/26035.
+TEST(ExtensionUpdaterTest, MAYBE_TestBlacklistDownloading) {
   ExtensionUpdaterTest::TestBlacklistDownloading();
 }
 
 TEST(ExtensionUpdaterTest, TestMultipleExtensionDownloading) {
   ExtensionUpdaterTest::TestMultipleExtensionDownloading();
 }
 
 
 // TODO(asargent) - (http://crbug.com/12780) add tests for:
 // -prodversionmin (shouldn't update if browser version too old)
 // -manifests & updates arriving out of order / interleaved
 // -Profile::GetDefaultRequestContext() returning null
 //  (should not crash, but just do check later)
 // -malformed update url (empty, file://, has query, has a # fragment, etc.)
 // -An extension gets uninstalled while updates are in progress (so it doesn't
 //  "come back from the dead")
 // -An extension gets manually updated to v3 while we're downloading v2 (ie
 //  you don't get downgraded accidentally)
 // -An update manifest mentions multiple updates