Add IsDynamicPartition API to easily check if a partition is dynamic

Test: treehugger
Change-Id: I655e4d6114a25c58857679985cd5e08581c0faab
diff --git a/aosp/dynamic_partition_control_android.cc b/aosp/dynamic_partition_control_android.cc
index 7ccc39a..ca12b3d 100644
--- a/aosp/dynamic_partition_control_android.cc
+++ b/aosp/dynamic_partition_control_android.cc
@@ -1283,4 +1283,14 @@
   return snapshot_->MapAllSnapshots(kMapSnapshotTimeout);
 }
 
+bool DynamicPartitionControlAndroid::IsDynamicPartition(
+    const std::string& partition_name) {
+  if (dynamic_partition_list_.empty() &&
+      GetDynamicPartitionsFeatureFlag().IsEnabled()) {
+    CHECK(ListDynamicPartitionsForSlot(source_slot_, &dynamic_partition_list_));
+  }
+  return std::find(dynamic_partition_list_.begin(),
+                   dynamic_partition_list_.end(),
+                   partition_name) != dynamic_partition_list_.end();
+}
 }  // namespace chromeos_update_engine