Fix typo in cleanspec.

Misspelled add-clean-step.

Change-Id: I6c341dfc6bac1dbfbc6970e421d6a54c1303cc90
diff --git a/chromium/CleanSpec.mk b/chromium/CleanSpec.mk
index 701709d..1d5b521 100644
--- a/chromium/CleanSpec.mk
+++ b/chromium/CleanSpec.mk
@@ -46,7 +46,7 @@
 $(call add-clean-step, rm -rf $(TARGET_OUT_JAVA_LIBRARIES)/webviewchromium.*)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/framework/webview)
 $(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/framework/webviewchromium.jar)
-$(call add-clean-stem, rm -rf $(PRODUCT_OUT)/system/priv-app/webviewchromium)
+$(call add-clean-step, rm -rf $(PRODUCT_OUT)/system/priv-app/webviewchromium)
 
 # ******************************************************************
 # NEWER CLEAN STEPS MUST BE AT THE END OF THE LIST ABOVE THIS BANNER