[Sync] Add support for loading, updating and querying delete journals in

sync/syncable/in_memory_directory_backing_store.cc

Index: sync/syncable/in_memory_directory_backing_store.cc
diff --git a/sync/syncable/in_memory_directory_backing_store.cc b/sync/syncable/in_memory_directory_backing_store.cc
index ec09d45c1bcc101118b03fac807444c70434a9ef..4df2dd3ff7b06ff7868fa727179feabae3715626 100644
--- a/sync/syncable/in_memory_directory_backing_store.cc
+++ b/sync/syncable/in_memory_directory_backing_store.cc
@@ -13,6 +13,7 @@ InMemoryDirectoryBackingStore::InMemoryDirectoryBackingStore(
 
 DirOpenResult InMemoryDirectoryBackingStore::Load(
     MetahandlesIndex* entry_bucket,
+    IdsIndex* delete_journals,
     Directory::KernelLoadInfo* kernel_load_info) {
   if (!db_->is_open()) {
     if (!db_->OpenInMemory())
@@ -26,6 +27,8 @@ DirOpenResult InMemoryDirectoryBackingStore::Load(
     return FAILED_DATABASE_CORRUPT;
   if (!LoadEntries(entry_bucket))
     return FAILED_DATABASE_CORRUPT;
+  if (!LoadDeleteJournals(delete_journals))
+    return FAILED_DATABASE_CORRUPT;
   if (!LoadInfo(kernel_load_info))
     return FAILED_DATABASE_CORRUPT;
   if (!VerifyReferenceIntegrity(*entry_bucket))