1 files changed, 30 insertions, 22 deletions

diff --git a/sync/syncable/directory_backing_store.cc b/sync/syncable/directory_backing_store.cc
index c5f1fd5..9d7f4fc 100644
--- a/sync/syncable/directory_backing_store.cc
+++ b/sync/syncable/directory_backing_store.cc
@@ -40,6 +40,9 @@ namespace syncable {
 // Increment this version whenever updating DB tables.
 const int32_t kCurrentDBVersion = 90;
 
+// The current database page size in Kilobytes.
+const int32_t kCurrentPageSizeKB = 32768;
+
 // Iterate over the fields of |entry| and bind each to |statement| for
 // updating.  Returns the number of args bound.
 void BindFields(const EntryKernel& entry,
@@ -260,7 +263,7 @@ void UploadModelTypeEntryCount(const int total_specifics_copies,
 
 DirectoryBackingStore::DirectoryBackingStore(const string& dir_name)
     : dir_name_(dir_name),
-      database_page_size_(32768),
+      database_page_size_(kCurrentPageSizeKB),
       needs_metas_column_refresh_(false),
       needs_share_info_column_refresh_(false) {
   DCHECK(base::ThreadTaskRunnerHandle::IsSet());
@@ -270,7 +273,7 @@ DirectoryBackingStore::DirectoryBackingStore(const string& dir_name)
 DirectoryBackingStore::DirectoryBackingStore(const string& dir_name,
                                              sql::Connection* db)
     : dir_name_(dir_name),
-      database_page_size_(32768),
+      database_page_size_(kCurrentPageSizeKB),
       db_(db),
       needs_metas_column_refresh_(false),
       needs_share_info_column_refresh_(false) {
@@ -413,14 +416,20 @@ bool DirectoryBackingStore::OpenInMemory() {
 }
 
 bool DirectoryBackingStore::InitializeTables() {
-  int page_size = 0;
-  if (GetDatabasePageSize(&page_size) && page_size == 4096) {
-    IncreasePageSizeTo32K();
-  }
+  if (!UpdatePageSizeIfNecessary())
+    return false;
+
   sql::Transaction transaction(db_.get());
   if (!transaction.Begin())
     return false;
 
+  if (!db_->DoesTableExist("share_version")) {
+    // Delete the existing database (if any), and create a fresh one.
+    DropAllTables();
+    if (!CreateTables())
+      return false;
+  }
+
   int version_on_disk = GetVersion();
 
   // Upgrade from version 67. Version 67 was widely distributed as the original
@@ -569,22 +578,14 @@ bool DirectoryBackingStore::InitializeTables() {
   // version.
   if (version_on_disk == kCurrentDBVersion && needs_column_refresh()) {
     if (!RefreshColumns())
-      version_on_disk = 0;
-  }
-
-  // A final, alternative catch-all migration to simply re-sync everything.
-  if (version_on_disk != kCurrentDBVersion) {
-    if (version_on_disk > kCurrentDBVersion)
-      return false;
-
-    // Fallback (re-sync everything) migration path.
-    DVLOG(1) << "Old/null sync database, version " << version_on_disk;
-    // Delete the existing database (if any), and create a fresh one.
-    DropAllTables();
-    if (!CreateTables())
       return false;
   }
 
+  // In case of error, let the caller decide whether to re-sync from scratch
+  // with a new database.
+  if (version_on_disk != kCurrentDBVersion)
+    return false;
+
   return transaction.Commit();
 }
 
@@ -1472,6 +1473,7 @@ bool DirectoryBackingStore::MigrateVersion89To90() {
 
 bool DirectoryBackingStore::CreateTables() {
   DVLOG(1) << "First run, creating tables";
+
   // Create two little tables share_version and share_info
   if (!db_->Execute(
           "CREATE TABLE share_version ("
@@ -1711,10 +1713,16 @@ bool DirectoryBackingStore::GetDatabasePageSize(int* page_size) {
   return true;
 }
 
-bool DirectoryBackingStore::IncreasePageSizeTo32K() {
-  if (!db_->Execute("PRAGMA page_size=32768;") || !Vacuum()) {
+bool DirectoryBackingStore::UpdatePageSizeIfNecessary() {
+  int page_size;
+  if (!GetDatabasePageSize(&page_size))
+    return false;
+  if (page_size == kCurrentPageSizeKB)
+    return true;
+  std::string update_page_size = base::StringPrintf(
+    "PRAGMA page_size=%i;", kCurrentPageSizeKB);
+  if (!db_->Execute(update_page_size.c_str()) || !Vacuum())
     return false;
-  }
   return true;
 }