Add FeatureFlag for Virtual AB Compression

Test: treehugger
Bug: 168554689
Change-Id: I732cd1ef55c5c4362ef88a640c2ca228f472af89
diff --git a/common/dynamic_partition_control_interface.h b/common/dynamic_partition_control_interface.h
index 7c2d0b0..22f6db8 100644
--- a/common/dynamic_partition_control_interface.h
+++ b/common/dynamic_partition_control_interface.h
@@ -56,6 +56,8 @@
 
   // Return the feature flags of Virtual A/B on this device.
   virtual FeatureFlag GetVirtualAbFeatureFlag() = 0;
+  // Return the feature flags of Virtual A/B Compression on this device.
+  virtual FeatureFlag GetVirtualAbCompressionFeatureFlag() = 0;
 
   // Attempt to optimize |operation|.
   // If successful, |optimized| contains an operation with extents that