[Sync] Split encryption state and logic out of PSS and SBHI.

components/sync/driver/data_type_manager.h

Index: components/sync/driver/data_type_manager.h
diff --git a/components/sync/driver/data_type_manager.h b/components/sync/driver/data_type_manager.h
index 91c65c58d5fc17668f32a646f79dd005371d6bf0..9454995e2e81fcd24b2acd0bb8638d7eaf9a837a 100644
--- a/components/sync/driver/data_type_manager.h
+++ b/components/sync/driver/data_type_manager.h
@@ -95,6 +95,9 @@ class DataTypeManager {
   // completes the set will be updated.
   virtual ModelTypeSet GetActiveDataTypes() const = 0;
 
+  // Whether or not we are syncing encryption keys.
+  virtual bool IsNigoriEnabled() const = 0;
+
   // The current state of the data type manager.
   virtual State state() const = 0;
 };