Increase page size for SyncData DB from 4K to maximum supported 32K

sync/syncable/directory_backing_store.h

Index: sync/syncable/directory_backing_store.h
diff --git a/sync/syncable/directory_backing_store.h b/sync/syncable/directory_backing_store.h
index 36a2f0afd2308b6ae99708f19267df6852cfdc30..79920378ce7c3ab65e53149ff980a01dd18be330 100644
--- a/sync/syncable/directory_backing_store.h
+++ b/sync/syncable/directory_backing_store.h
@@ -44,6 +44,10 @@ struct ColumnSpec;
 // in tests.  The concrete class used in non-test scenarios is
 // OnDiskDirectoryBackingStore.
 class SYNC_EXPORT_PRIVATE DirectoryBackingStore : public base::NonThreadSafe {
+  friend class DirectoryBackingStoreTest;
+  FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest,
+                           IncreaseDatabasePageSizeFrom4KTo32K);
+
  public:
   explicit DirectoryBackingStore(const std::string& dir_name);
   virtual ~DirectoryBackingStore();
@@ -145,6 +149,12 @@ class SYNC_EXPORT_PRIVATE DirectoryBackingStore : public base::NonThreadSafe {
   bool SetVersion(int version);
   int GetVersion();
 
+  bool GetDatabasePageSize(int* page_size);
+  bool IsSyncBackingDatabase32KEnabled();
+  bool IncreasePageSizeTo32K();
+  bool Vacuum();
+  int databasePageSize_;
+
   bool MigrateToSpecifics(const char* old_columns,
                           const char* specifics_column,
                           void(*handler_function) (