Remove use of deprecated base::ListValue::Append(Value*) overload in extensions.

BUG=581865

Review-Url: https://codereview.chromium.org/2323993004
Cr-Commit-Position: refs/heads/master@{#418568}
diff --git a/extensions/browser/computed_hashes.cc b/extensions/browser/computed_hashes.cc
index bf0cf98..0758506 100644
--- a/extensions/browser/computed_hashes.cc
+++ b/extensions/browser/computed_hashes.cc
@@ -4,6 +4,9 @@
 
 #include "extensions/browser/computed_hashes.h"
 
+#include <memory>
+#include <utility>
+
 #include "base/base64.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
@@ -133,13 +136,13 @@
 void ComputedHashes::Writer::AddHashes(const base::FilePath& relative_path,
                                        int block_size,
                                        const std::vector<std::string>& hashes) {
-  base::DictionaryValue* dict = new base::DictionaryValue();
+  std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
   base::ListValue* block_hashes = new base::ListValue();
-  file_list_->Append(dict);
   dict->SetString(kPathKey,
                   relative_path.NormalizePathSeparatorsTo('/').AsUTF8Unsafe());
   dict->SetInteger(kBlockSizeKey, block_size);
   dict->Set(kBlockHashesKey, block_hashes);
+  file_list_->Append(std::move(dict));
 
   for (std::vector<std::string>::const_iterator i = hashes.begin();
        i != hashes.end();