Allow for multiple preferred densities in the strip command.

Test: Unit tests pass.

Change-Id: I1f27ac8c36ff3489e4c8e4fce7f3d9cb31df6906
diff --git a/tools/aapt2/split/TableSplitter.h b/tools/aapt2/split/TableSplitter.h
index 1ae3271..6aec257 100644
--- a/tools/aapt2/split/TableSplitter.h
+++ b/tools/aapt2/split/TableSplitter.h
@@ -34,14 +34,14 @@
 
 struct TableSplitterOptions {
   /**
-   * The preferred density to keep in the table, stripping out all others.
+   * The preferred densities to keep in the table, stripping out all others.
+   * If empty, no stripping is done.
    */
-  Maybe<uint16_t> preferred_density;
+  std::vector<uint16_t> preferred_densities;
 
   /**
    * Configuration filter that determines which resource configuration values
-   * end up in
-   * the final table.
+   * end up in the final table.
    */
   IConfigFilter* config_filter = nullptr;
 };