Use about:blank as the failback URL if the filter denies a navigation.

chrome/browser/geolocation/chrome_geolocation_permission_context_unittest.cc

 // Copyright (c) 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.
 
 #include <set>
 #include <string>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/hash_tables.h"
@@ skipping 393 matching lines @@
 
   EXPECT_EQ(CONTENT_SETTING_ALLOW,
       profile()->GetHostContentSettingsMap()->GetContentSetting(
           requesting_frame_1,
           requesting_frame_0,
           CONTENT_SETTINGS_TYPE_GEOLOCATION,
           std::string()));
 }
 
 TEST_F(GeolocationPermissionContextTests, InvalidURL) {
-  GURL invalid_embedder;
-  GURL requesting_frame("about:blank");
+  GURL invalid_embedder("about:blank");
+  GURL requesting_frame;
   NavigateAndCommit(invalid_embedder);
   EXPECT_EQ(0U, infobar_tab_helper()->infobar_count());
   RequestGeolocationPermission(
       process_id(), render_id(), bridge_id(), requesting_frame);
   EXPECT_EQ(0U, infobar_tab_helper()->infobar_count());
   CheckPermissionMessageSent(bridge_id(), false);
 }
 
 TEST_F(GeolocationPermissionContextTests, SameOriginMultipleTabs) {
   GURL url_a("http://www.example.com/geolocation");
@@ skipping 165 matching lines @@
   ASSERT_FALSE(infobar_0->ShouldExpire(details));
   // Commit the "GoBack()" above, and ensure the infobar is now expired.
   contents()->CommitPendingNavigation();
   details.entry = contents()->GetController().GetLastCommittedEntry();
   ASSERT_TRUE(infobar_0->ShouldExpire(details));
 
   // Delete the tab contents.
   DeleteContents();
   infobar_0->InfoBarClosed();
 }