Expose whether a file was compressed before being loaded in memory.

This is useful when we want to write an APK and keep the same
compression parameters as the original APK.

Test: Unit tests pass.

Change-Id: I3afcae1c8727e429b08c9ac7359cf0789ff4abfc

tools/aapt2/io/File.h

@@ -63,6 +63,11 @@ class IFile {
 
   IFile* CreateFileSegment(size_t offset, size_t len);
 
+  /** Returns whether the file was compressed before it was stored in memory. */
+  virtual bool WasCompressed() {
+    return false;
+  }
+
  private:
   // Any segments created from this IFile need to be owned by this IFile, so
   // keep them

tools/aapt2/io/ZipArchive.cpp

@@ -59,6 +59,10 @@ std::unique_ptr<IData> ZipFile::OpenAsData() {
 
 const Source& ZipFile::GetSource() const { return source_; }
 
+bool ZipFile::WasCompressed() {
+  return zip_entry_.method != kCompressStored;
+}
+
 ZipFileCollectionIterator::ZipFileCollectionIterator(
     ZipFileCollection* collection)
     : current_(collection->files_.begin()), end_(collection->files_.end()) {}

tools/aapt2/io/ZipArchive.h

@@ -40,6 +40,7 @@ class ZipFile : public IFile {
 
   std::unique_ptr<IData> OpenAsData() override;
   const Source& GetSource() const override;
+  bool WasCompressed() override;
 
  private:
   ZipArchiveHandle zip_handle_;