AAPT2: Support building, linking, and merging static libraries

Android static libraries are like APKs but they contain much more debugging
and source information. We need to treat them differently in 3 ways:

1) When building a static library, we skip things like ID assignment and
   product/config stripping. Source information is emitted as well.
2) When building a static library and linking against another
   static library, we don't want to merge, we want to simply reference.
3) When building an app that uses static libraries, we want to merge
   the static library under the same package with or without mangling.

Bug:25958912
Change-Id: I425e032857936a3e83173c1edc2a6cdc6020b842
diff --git a/tools/aapt2/link/TableMerger.h b/tools/aapt2/link/TableMerger.h
index b3c22dd..80c2a5e 100644
--- a/tools/aapt2/link/TableMerger.h
+++ b/tools/aapt2/link/TableMerger.h
@@ -65,13 +65,17 @@
 
     /**
      * Merges resources from the same or empty package. This is for local sources.
+     * An io::IFileCollection is optional and used to find the referenced Files and process them.
      */
-    bool merge(const Source& src, ResourceTable* table);
+    bool merge(const Source& src, ResourceTable* table,
+               io::IFileCollection* collection = nullptr);
 
     /**
      * Merges resources from an overlay ResourceTable.
+     * An io::IFileCollection is optional and used to find the referenced Files and process them.
      */
-    bool mergeOverlay(const Source& src, ResourceTable* table);
+    bool mergeOverlay(const Source& src, ResourceTable* table,
+                      io::IFileCollection* collection = nullptr);
 
     /**
      * Merges resources from the given package, mangling the name. This is for static libraries.
@@ -104,7 +108,7 @@
 
     bool mergeFileImpl(const ResourceFile& fileDesc, io::IFile* file, bool overlay);
 
-    bool mergeImpl(const Source& src, ResourceTable* srcTable,
+    bool mergeImpl(const Source& src, ResourceTable* srcTable, io::IFileCollection* collection,
                    bool overlay, bool allowNew);
 
     bool doMerge(const Source& src, ResourceTable* srcTable, ResourceTablePackage* srcPackage,