Remove preloaded URLs from back stack when preloading fails.

Bug: 5114365
Change-Id: Iaef0c062ac1ee2ea6e3cde8699d67a0cc4ff1a56
diff --git a/src/com/android/browser/PreloadedTabControl.java b/src/com/android/browser/PreloadedTabControl.java
index d2482a4..824c00b 100644
--- a/src/com/android/browser/PreloadedTabControl.java
+++ b/src/com/android/browser/PreloadedTabControl.java
@@ -82,8 +82,9 @@
                 if (!called) {
                     if (LOGD_ENABLED) Log.d(LOGTAG, "Query not submitted; falling back");
                     loadUrl(fallbackUrl, fallbackHeaders);
+                    // make sure that the failed, preloaded URL is cleared from the back stack
+                    mTab.clearBackStackWhenItemAdded(fallbackUrl);
                 }
-                mTab.getWebView().clearHistory();
             }});
         return true;
     }