Move closure_blocks_leopard_compat to base now that it's used by two modules.

content/content_tests.gypi

Index: content/content_tests.gypi
===================================================================
--- content/content_tests.gypi	(revision 124212)
+++ content/content_tests.gypi	(working copy)
@@ -223,7 +223,6 @@
         'browser/in_process_webkit/dom_storage_unittest.cc',
         'browser/in_process_webkit/indexed_db_quota_client_unittest.cc',
         'browser/in_process_webkit/webkit_thread_unittest.cc',
-        'browser/mac/closure_blocks_leopard_compat_unittest.cc',
         'browser/mach_broker_mac_unittest.cc',
         'browser/notification_service_impl_unittest.cc',
         'browser/plugin_loader_posix_unittest.cc',
@@ -350,11 +349,6 @@
             ['exclude', '^browser/renderer_host/gtk_key_bindings_handler_unittest.cc'],
           ],
         }],
-        ['OS=="mac"', {
-          'dependencies': [
-            'closure_blocks_leopard_compat',
-          ],
-        }],
         ['OS == "win" or (toolkit_uses_gtk == 1 and selinux == 0)', {
           'dependencies': [
             '../sandbox/sandbox.gyp:sandbox',