Remove duplicated code from sync related unit tests.

sync/api/fake_sync_change_processor.cc

Index: sync/api/fake_sync_change_processor.cc
diff --git a/sync/api/fake_sync_change_processor.cc b/sync/api/fake_sync_change_processor.cc
index f8d2f40ccacd24c8eaf6c232197f5e677a9132c0..83d669e1b2804893633c0d5bd835d8f805eef73e 100644
--- a/sync/api/fake_sync_change_processor.cc
+++ b/sync/api/fake_sync_change_processor.cc
@@ -3,6 +3,8 @@
 // found in the LICENSE file.
 
 #include "sync/api/fake_sync_change_processor.h"
+#include "sync/api/sync_change.h"
+#include "sync/api/sync_data.h"
 
 namespace syncer {
 
@@ -13,6 +15,8 @@ FakeSyncChangeProcessor::~FakeSyncChangeProcessor() {}
 syncer::SyncError FakeSyncChangeProcessor::ProcessSyncChanges(
       const tracked_objects::Location& from_here,
       const syncer::SyncChangeList& change_list) {
+  change_list_.insert(
+      change_list_.end(), change_list.begin(), change_list.end());
   return syncer::SyncError();
 }
 
@@ -21,4 +25,12 @@ syncer::SyncDataList FakeSyncChangeProcessor::GetAllSyncData(
   return syncer::SyncDataList();
 }
 
+const syncer::SyncChangeList& FakeSyncChangeProcessor::changes() const {
+  return change_list_;
+}
+
+syncer::SyncChangeList& FakeSyncChangeProcessor::changes() {
+  return change_list_;
+}
+
 }  // namespace syncer