Try --force-uninstall param to see if that fixes installer tests.

chrome/test/mini_installer_test/test.cc

Index: chrome/test/mini_installer_test/test.cc
diff --git a/chrome/test/mini_installer_test/test.cc b/chrome/test/mini_installer_test/test.cc
index 1ddb44b53359ba8e0a30642caca00e9e5a284d82..a2e64195976778c8d7106908908f5170e8897f3d 100644
--- a/chrome/test/mini_installer_test/test.cc
+++ b/chrome/test/mini_installer_test/test.cc
@@ -60,7 +60,7 @@ TEST_F(MiniInstallTest, DISABLED_MiniInstallerSystemInstallTest) {
   }
 }
 
-TEST_F(MiniInstallTest, DISABLED_MiniInstallerUserInstallTest) {
+TEST_F(MiniInstallTest, MiniInstallerUserInstallTest) {
   if (win_util::GetWinVersion() < win_util::WINVERSION_VISTA) {
     ChromeMiniInstaller installer(mini_installer_constants::kUserInstall);
     installer.Install();