Sync: Avoid 3 passes over SyncDarta DB when loading the directory from the disk

sync/syncable/deferred_on_disk_directory_backing_store_unittest.cc

Index: sync/syncable/deferred_on_disk_directory_backing_store_unittest.cc
diff --git a/sync/syncable/deferred_on_disk_directory_backing_store_unittest.cc b/sync/syncable/deferred_on_disk_directory_backing_store_unittest.cc
index fbba75e537ce0700a8f3984aa862f57bb2a3e0f9..020eeb447e2024a54e75e2b9e393186ab324f581 100644
--- a/sync/syncable/deferred_on_disk_directory_backing_store_unittest.cc
+++ b/sync/syncable/deferred_on_disk_directory_backing_store_unittest.cc
@@ -31,6 +31,7 @@ class DeferredOnDiskDirectoryBackingStoreTest : public testing::Test {
   base::FilePath db_path_;
   Directory::MetahandlesMap handles_map_;
   JournalIndex delete_journals_;
+  MetahandleSet metahandles_to_purge_;
   Directory::KernelLoadInfo kernel_load_info_;
 };
 
@@ -38,8 +39,9 @@ class DeferredOnDiskDirectoryBackingStoreTest : public testing::Test {
 TEST_F(DeferredOnDiskDirectoryBackingStoreTest, Load) {
   DeferredOnDiskDirectoryBackingStore store("test", db_path_);
   EXPECT_EQ(OPENED, store.Load(&handles_map_, &delete_journals_,
-                               &kernel_load_info_));
+                               &metahandles_to_purge_, &kernel_load_info_));
   EXPECT_TRUE(delete_journals_.empty());
+  EXPECT_TRUE(metahandles_to_purge_.empty());
   ASSERT_EQ(1u, handles_map_.size());   // root node
   ASSERT_TRUE(handles_map_.count(1));
   EntryKernel* root = handles_map_[1];
@@ -55,7 +57,7 @@ TEST_F(DeferredOnDiskDirectoryBackingStoreTest,
     // Open and close.
     DeferredOnDiskDirectoryBackingStore store("test", db_path_);
     EXPECT_EQ(OPENED, store.Load(&handles_map_, &delete_journals_,
-                                 &kernel_load_info_));
+                                 &metahandles_to_purge_, &kernel_load_info_));
   }
 
   EXPECT_FALSE(base::PathExists(db_path_));
@@ -68,7 +70,7 @@ TEST_F(DeferredOnDiskDirectoryBackingStoreTest,
     // Open and close.
     DeferredOnDiskDirectoryBackingStore store("test", db_path_);
     EXPECT_EQ(OPENED, store.Load(&handles_map_, &delete_journals_,
-                                 &kernel_load_info_));
+                                 &metahandles_to_purge_, &kernel_load_info_));
 
     Directory::SaveChangesSnapshot snapshot;
     store.SaveChanges(snapshot);
@@ -83,7 +85,7 @@ TEST_F(DeferredOnDiskDirectoryBackingStoreTest, PersistWhenSavingValidChanges) {
     // Open and close.
     DeferredOnDiskDirectoryBackingStore store("test", db_path_);
     EXPECT_EQ(OPENED, store.Load(&handles_map_, &delete_journals_,
-                                 &kernel_load_info_));
+                                 &metahandles_to_purge_, &kernel_load_info_));
 
     Directory::SaveChangesSnapshot snapshot;
     EntryKernel* entry = new EntryKernel();
@@ -98,8 +100,9 @@ TEST_F(DeferredOnDiskDirectoryBackingStoreTest, PersistWhenSavingValidChanges) {
 
   ASSERT_TRUE(base::PathExists(db_path_));
   OnDiskDirectoryBackingStore read_store("test", db_path_);
-  EXPECT_EQ(OPENED, read_store.Load(&handles_map_, &delete_journals_,
-                                    &kernel_load_info_));
+  EXPECT_EQ(OPENED,
+            read_store.Load(&handles_map_, &delete_journals_,
+                            &metahandles_to_purge_, &kernel_load_info_));
   ASSERT_EQ(2u, handles_map_.size());
   ASSERT_TRUE(handles_map_.count(1));     // root node
   ASSERT_TRUE(handles_map_.count(2));