Sync/Valgrind: Add gmock printers for SyncChange, SyncData, SyncError.

chrome/browser/sync/api/sync_change.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_SYNC_API_SYNC_CHANGE_H_
 #define CHROME_BROWSER_SYNC_API_SYNC_CHANGE_H_
 #pragma once
 
+#include <iosfwd>
 #include <string>
 #include <vector>
 
 #include "chrome/browser/sync/api/sync_data.h"
 
 // A SyncChange object reflects a change to a piece of synced data. The change
 // can be either a delete, add, or an update. All data relevant to the change
 // is encapsulated within the SyncChange, which, once created, is immutable.
 // Note: it is safe and cheap to pass these by value or make copies, as they do
 // not create deep copies of their internal data.
@@ skipping 22 matching lines @@
   //                Require only valid specifics when coming from the syncer.
   bool IsValid() const;
 
   // Getters.
   SyncChangeType change_type() const;
   SyncData sync_data() const;
 
   // Returns a string representation of |change_type|.
   static std::string ChangeTypeToString(SyncChangeType change_type);
 
+  // Returns a string representation of the entire object. Used for gmock
+  // printing method, PrintTo.
+  std::string ToString() const;
+
  private:
   SyncChangeType change_type_;
 
   // An immutable container for the data of this SyncChange. Whenever
   // SyncChanges are copied, they copy references to this data.
   SyncData sync_data_;
 };
 
+// gmock printer helper.
+void PrintTo(const SyncChange& sync_change, std::ostream* os);
+
 #endif  // CHROME_BROWSER_SYNC_API_SYNC_CHANGE_H_