Revert "chromeos: Move files in //ash/common to //ash, part 3"

ash/test/ash_test.h

Index: ash/test/ash_test.h
diff --git a/ash/test/ash_test.h b/ash/test/ash_test.h
index 61b542a64b9601b1185a30aa999bcc8cc71a5539..0eccb70d006b238501f72bf036daec57c4ce4e35 100644
--- a/ash/test/ash_test.h
+++ b/ash/test/ash_test.h
@@ -55,7 +55,7 @@ class WindowOwner {
 
 // Base class for ash tests. This class calls through to AshTestImpl for the
 // real implementation. This class exists so that tests can be written to
-// run in both mus ash and classic ash.
+// ash/common and run in both mus and aura.
 //
 // The implementation of AshTestImpl that is used depends upon gn targets. To
 // use the aura backend depend on "//ash/test:ash_with_aura_test_support." The