Enable the volume slider in Ash for windows.

ash/test/ash_test_helper_unittest.cc

Index: ash/test/ash_test_helper_unittest.cc
diff --git a/ash/test/ash_test_helper_unittest.cc b/ash/test/ash_test_helper_unittest.cc
index 52e73fb9a79687ee514151d9f29337b170c08570..547cafa82db0aa157a9cb82e9589f6eb2422c599 100644
--- a/ash/test/ash_test_helper_unittest.cc
+++ b/ash/test/ash_test_helper_unittest.cc
@@ -8,6 +8,10 @@
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/views/widget/widget.h"
 
+#if defined(OS_WIN)
+#include "base/win/windows_version.h"
+#endif
+
 // Tests for AshTestHelper. Who will watch the watchers? And who will test
 // the tests?
 class AshTestHelperTest : public testing::Test {
@@ -40,6 +44,11 @@ class AshTestHelperTest : public testing::Test {
 // Ensure that we have initialized enough of Ash to create and show a window.
 TEST_F(AshTestHelperTest, AshTestHelper) {
   // Check initial state.
+#if defined(OS_WIN)
+  // Ash doesn't run on versions of Windows prior to Win7.
+  if (base::win::GetVersion() < base::win::VERSION_WIN7)
+    return;
+#endif
   EXPECT_TRUE(ash_test_helper()->message_loop());
   EXPECT_TRUE(ash_test_helper()->test_shell_delegate());
   EXPECT_TRUE(ash_test_helper()->CurrentContext());