SF: Add TransactionHandler

- migrate transaction queueing and flushing into
  a new class and remove dependencies from
  other components.
- Add a filter interface for other components to
  participate in transactionready logic.

Test: presubmit
Bug: 238781169
Change-Id: Ia4da386cd72058126f6f765adafb9cb4d15b1d2b
diff --git a/libs/gui/LayerState.cpp b/libs/gui/LayerState.cpp
index 4d5978c..2759c58 100644
--- a/libs/gui/LayerState.cpp
+++ b/libs/gui/LayerState.cpp
@@ -634,7 +634,7 @@
 }
 
 bool layer_state_t::hasValidBuffer() const {
-    return bufferData && (bufferData->buffer || bufferData->cachedBuffer.isValid());
+    return bufferData && (bufferData->hasBuffer() || bufferData->cachedBuffer.isValid());
 }
 
 status_t layer_state_t::matrix22_t::write(Parcel& output) const {