Correct const accessors in base/values.(h|cc)

sync/internal_api/syncapi_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.
 
 // Unit tests for the SyncApi. Note that a lot of the underlying
 // functionality is provided by the Syncable layer, which has its own
 // unit tests. We'll test SyncApi specific things in this harness.
 
 #include <cstddef>
 #include <map>
@@ skipping 566 matching lines @@
   }
   if (is_detailed) {
     ExpectInt64Value(node.GetParentId(), value, "parentId");
     ExpectTimeValue(node.GetModificationTime(), value, "modificationTime");
     ExpectInt64Value(node.GetExternalId(), value, "externalId");
     ExpectInt64Value(node.GetPredecessorId(), value, "predecessorId");
     ExpectInt64Value(node.GetSuccessorId(), value, "successorId");
     ExpectInt64Value(node.GetFirstChildId(), value, "firstChildId");
     {
       scoped_ptr<DictionaryValue> expected_entry(node.GetEntry()->ToValue());
-      Value* entry = NULL;
+      const Value* entry = NULL;
       EXPECT_TRUE(value.Get("entry", &entry));
       EXPECT_TRUE(Value::Equals(entry, expected_entry.get()));
     }
     EXPECT_EQ(11u, value.size());
   } else {
     EXPECT_EQ(4u, value.size());
   }
 }
 
 }  // namespace
@@ skipping 2023 matching lines @@
   // Ensure only bookmarks and nigori lost their progress marker. Preferences
   // should still have it.
   partial_types =
       sync_manager_.GetTypesWithEmptyProgressMarkerToken(ModelTypeSet::All());
   EXPECT_TRUE(partial_types.Has(NIGORI));
   EXPECT_TRUE(partial_types.Has(BOOKMARKS));
   EXPECT_FALSE(partial_types.Has(PREFERENCES));
 }
 
 }  // namespace