Update next_id when loading sync DB

sync/syncable/syncable_unittest.cc

Index: sync/syncable/syncable_unittest.cc
diff --git a/sync/syncable/syncable_unittest.cc b/sync/syncable/syncable_unittest.cc
index cf34a94ec93eef46ec419698ce3602683cbbbd4e..02af9aec6e43453ae303d6659b4c99a3c57fdf8c 100644
--- a/sync/syncable/syncable_unittest.cc
+++ b/sync/syncable/syncable_unittest.cc
@@ -520,6 +520,15 @@ class SyncableDirectoryTest : public testing::Test {
   // not have any pointers to the directory (open transactions included)
   // when you call this.
   DirOpenResult SimulateSaveAndReloadDir();
+
+  // This function will close and re-open the directory without saving any
+  // pending changes.  This is intended to simulate the recovery from a crash
+  // scenario.  The same warnings for SimulateSaveAndReloadDir apply here.
+  DirOpenResult SimulateCrashAndReloadDir();
+
+ private:
+  // A helper function for Simulate{Save,Crash}AndReloadDir.
+  DirOpenResult ReloadDirImpl();
 };
 
 TEST_F(SyncableDirectoryTest, TakeSnapshotGetsMetahandlesToPurge) {
@@ -1261,6 +1270,27 @@ TEST_F(SyncableDirectoryTest,
   EXPECT_EQ(OPENED, SimulateSaveAndReloadDir());
 }
 
+// Ask the directory to generate a unique ID.  Close and re-open the database
+// without saving, then ask for another unique ID.  Verify IDs are not reused.
+// This scenario simulates a crash within the first few seconds of operation.
+TEST_F(SyncableDirectoryTest, LocalIdReuseTest) {
+  Id pre_crash_id = dir_->NextId();
+  SimulateCrashAndReloadDir();
+  Id post_crash_id = dir_->NextId();
+  EXPECT_NE(pre_crash_id, post_crash_id);
+}
+
+// Ask the directory to generate a unique ID.  Save the directory.  Close and
+// re-open the database without saving, then ask for another unique ID.  Verify
+// IDs are not reused.  This scenario simulates a steady-state crash.
+TEST_F(SyncableDirectoryTest, LocalIdReuseTestWithSave) {
+  Id pre_crash_id = dir_->NextId();
+  dir_->SaveChanges();
+  SimulateCrashAndReloadDir();
+  Id post_crash_id = dir_->NextId();
+  EXPECT_NE(pre_crash_id, post_crash_id);
+}
+
 // Ensure that the unsynced, is_del and server unkown entries that may have been
 // left in the database by old clients will be deleted when we open the old
 // database.
@@ -1721,6 +1751,14 @@ DirOpenResult SyncableDirectoryTest::SimulateSaveAndReloadDir() {
   if (!dir_->SaveChanges())
     return FAILED_IN_UNITTEST;
 
+  return ReloadDirImpl();
+}
+
+DirOpenResult SyncableDirectoryTest::SimulateCrashAndReloadDir() {
+  return ReloadDirImpl();
+}
+
+DirOpenResult SyncableDirectoryTest::ReloadDirImpl() {
   // Do some tricky things to preserve the backing store.
   DirectoryBackingStore* saved_store = dir_->store_.release();