Fix NULL dereference if a extension subpermission is removed.

chrome/common/extensions/permissions/media_galleries_permission_unittest.cc

 // Copyright (c) 2013 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.
 
 // These tests make sure MediaGalleriesPermission values are parsed correctly.
 
 #include "base/values.h"
 #include "extensions/common/permissions/api_permission.h"
 #include "extensions/common/permissions/media_galleries_permission.h"
 #include "extensions/common/permissions/media_galleries_permission_data.h"
@@ skipping 140 matching lines @@
 
   // Multiple unknown permissions.
   value.reset(new base::ListValue());
   value->AppendString("Unknown1");
   value->AppendString("Unknown2");
   EXPECT_TRUE(permission->FromValue(value.get(), &error, &unhandled));
   EXPECT_TRUE(error.empty());
   EXPECT_EQ(2U, unhandled.size());
   error.clear();
   unhandled.clear();
+
+  // Unnknown with a NULL argument.
+  value.reset(new base::ListValue());
+  value->AppendString("Unknown1");
+  EXPECT_FALSE(permission->FromValue(value.get(), &error, NULL));
+  EXPECT_FALSE(error.empty());
+  error.clear();
 }
 
 TEST(MediaGalleriesPermissionTest, Equal) {
   const APIPermissionInfo* permission_info =
     PermissionsInfo::GetInstance()->GetByID(APIPermission::kMediaGalleries);
 
   scoped_ptr<APIPermission> permission1(
       permission_info->CreateAPIPermission());
   scoped_ptr<APIPermission> permission2(
       permission_info->CreateAPIPermission());
@@ skipping 101 matching lines @@
 
   vtmp = permission1->ToValue();
   ASSERT_TRUE(vtmp);
   ASSERT_TRUE(permission2->FromValue(vtmp.get(), NULL, NULL));
   EXPECT_TRUE(permission1->Equal(permission2.get()));
 }
 
 }  // namespace
 
 }  // namespace extensions