Migration unit tests to web database for missing images on the search ballot

chrome/browser/webdata/web_database.cc

 // Copyright (c) 2010 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 "chrome/browser/webdata/web_database.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 #include <string>
@@ skipping 142 matching lines @@
 //   has_all_images      Do we have all the images?
 //
 ////////////////////////////////////////////////////////////////////////////////
 
 using base::Time;
 
 namespace {
 
 typedef std::vector<Tuple3<int64, string16, string16> > AutofillElementList;
 
-// Current version number.
+// Current version number.  Note: when changing the current version number,
+// corresponding changes must happen in the unit tests, and new migration test
+// added.  See |WebDatabaseMigrationTest::kCurrentTestedVersionNumber|.
 const int kCurrentVersionNumber = 25;
 const int kCompatibleVersionNumber = 25;
 const int kUrlIdPosition = 14;
 
 // Keys used in the meta table.
 const char* kDefaultSearchProviderKey = "Default Search Provider ID";
 const char* kBuiltinKeywordVersion = "Builtin Keyword Version";
 
 // The maximum length allowed for form data.
 const size_t kMaxDataLength = 1024;
@@ skipping 1857 matching lines @@
 
     // Add successive versions here.  Each should set the version number and
     // compatible version number as appropriate, then fall through to the next
     // case.
 
     case kCurrentVersionNumber:
       // No migration needed.
       return;
   }
 }