[Android] Fix findbugs errors.

content/shell/android/java/src/org/chromium/content_shell/Shell.java

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.content_shell;
 
 import android.content.Context;
 import android.graphics.drawable.ClipDrawable;
 import android.text.TextUtils;
 import android.util.AttributeSet;
@@ skipping 176 matching lines @@
         mContentViewCore.getContainerView().clearFocus();
         mContentViewCore.getContainerView().requestFocus();
     }
 
     /**
      * Given an URL, this performs minimal sanitizing to ensure it will be valid.
      * @param url The url to be sanitized.
      * @return The sanitized URL.
      */
     public static String sanitizeUrl(String url) {
-        if (url == null) return url;
+        if (url == null) return null;
         if (url.startsWith("www.") || url.indexOf(":") == -1) url = "http://" + url;
         return url;
     }
 
     private void initializeNavigationButtons() {
         mPrevButton = (ImageButton) findViewById(R.id.prev);
         mPrevButton.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View v) {
                 if (mContentViewCore.canGoBack()) mContentViewCore.goBack();
@@ skipping 110 matching lines @@
                 Context.INPUT_METHOD_SERVICE);
         if (visible) {
             imm.showSoftInput(mUrlTextView, InputMethodManager.SHOW_IMPLICIT);
         } else {
             imm.hideSoftInputFromWindow(mUrlTextView.getWindowToken(), 0);
         }
     }
 
     private static native void nativeCloseShell(long shellPtr);
 }