More style nits.

chrome/browser/history/query_parser.cc

Index: chrome/browser/history/query_parser.cc
diff --git a/chrome/browser/history/query_parser.cc b/chrome/browser/history/query_parser.cc
index f17dad6bc70cb3f3a816d6a2c71962909100c8ff..6bfaa7fcb6780bb4e5efa53d03df9776d2c1e9df 100644
--- a/chrome/browser/history/query_parser.cc
+++ b/chrome/browser/history/query_parser.cc
@@ -66,7 +66,8 @@ void CoalseAndSortMatchPositions(Snippet::MatchPositions* matches) {
 // A QueryNodeWord is a single word in the query.
 class QueryNodeWord : public QueryNode {
  public:
-  QueryNodeWord(const std::wstring& word) : word_(word), literal_(false) {}
+  explicit QueryNodeWord(const std::wstring& word)
+      : word_(word), literal_(false) {}
   virtual ~QueryNodeWord() {}
   virtual int AppendToSQLiteQuery(std::wstring* query) const;
   virtual bool IsWord() const { return true; }