Add a location type to describe where to search for a file

The location field by default means the file is in local disk or one of the zip files.
This is the default location type file. Add a second type to search for
the file in the AB artifacts as some projects may skip the zip files.

Change-Id: I2b91fabb3e7a17ee879765cb83394180fefb26d9
diff --git a/cmd/symbols_map/symbols_map_proto/symbols_map.proto b/cmd/symbols_map/symbols_map_proto/symbols_map.proto
index 693fe3e..a76d171 100644
--- a/cmd/symbols_map/symbols_map_proto/symbols_map.proto
+++ b/cmd/symbols_map/symbols_map_proto/symbols_map.proto
@@ -37,6 +37,21 @@
 
   // type is the type of the mapping, either ELF or R8.
   optional Type type = 3;
+
+  // LocationType is the place where to look for the file with the given
+  // identifier.
+  Enum LocationType {
+    // ZIP denotes the file with the given identifier is in the distribuited
+    // symbols.zip or proguard_dict.zip files, or the local disc.
+    ZIP = 0;
+    // AB denotes the file with the given identifier is in the AB artifacts but
+    // not in a symbols.zip or proguard_dict.zip.
+    AB = 1;
+  }
+
+  // location_type is the Location Type that dictates where to search for the
+  // file with the given identifier. Defaults to ZIP if not present.
+  optional LocationType location_type = 4;
 }
 
 message Mappings {