Remove all excludes for 28439. Only valgrind bot(1) is failing and this must be something else.

tools/valgrind/gtest_exclude/ui_tests.gtest_linux.txt

Index: tools/valgrind/gtest_exclude/ui_tests.gtest_linux.txt
diff --git a/tools/valgrind/gtest_exclude/ui_tests.gtest_linux.txt b/tools/valgrind/gtest_exclude/ui_tests.gtest_linux.txt
index 86a3270da62dd260e526af5338358ddc53313925..e9bf269955b25fa10d4e6424fb0097d4c5ed872d 100644
--- a/tools/valgrind/gtest_exclude/ui_tests.gtest_linux.txt
+++ b/tools/valgrind/gtest_exclude/ui_tests.gtest_linux.txt
@@ -25,37 +25,3 @@ SessionHistoryTest.BasicBackForward
 # Times out on CrOS pretty often. http://crbug.com/92535
 AutomatedUITestBase.FindInPage
 
-# mmap error. See http://crbug.com/28439
-AutomatedUITestBase.Home
-AutomatedUITestBase.Navigate
-AutomatedUITestBase.OpenNewTab
-AutomationProxyTest.GetCurrentURL
-AutomationProxyTest.GoBackForward
-AutomationProxyTest5.TestLifetimeOfDomAutomationController
-AutomationProxyVisibleTest.AppendTab
-ErrorPageTest.IFrameDNSError_GoBackAndForward
-HistoryTester.VerifyHistoryLength1
-LocaleTestsHe.TestStart
-LoginPromptTest.CancelRedundantAuths
-MultipartResponseUITest.SingleVisit
-NPAPITesterBase.GetURL
-NPAPITesterBase.NPObjectProxy
-NPAPITesterBase.PrivateDisabled
-NoStartupWindowTest.NoStartupWindowBasicTest
-OptionsUITest.LoadOptionsByURL
-OutOfProcessPPAPITest.Broker
-OutOfProcessPPAPITest.Core
-PPAPITest.Buffer
-PPAPITest.FileRef
-PPAPITest.Graphics2D
-PPAPITest.URLLoader
-ProcessSingletonLinuxTest.CreateChecksCompatibilitySocket
-ProcessSingletonLinuxTest.CreateFailsWithExistingBrowser
-RedirectTest.ClientFragments
-ResourceDispatcherTest.CrossOriginRedirectBlocked
-ResourceDispatcherTest.CrossSiteNavigationErrorPage
-ResourceDispatcherTest.CrossSiteNavigationNonBuffered
-RunInBackgroundTest.RunInBackgroundBasicTest
-SearchProviderTest.TestIsSearchProviderInstalled
-WorkerFileSystemTest.Persistent
-WorkerFileSystemTest.Temporary