Resource Path Obfuscation

This CL allows aapt2 to obfuscate resource paths within the output apk
and move resources to shorter obfuscated paths. This reduces apk size
when there is a large number of resources since the path metadata exists
in 4 places in the apk.

This CL adds two arguments to aapt2, one to enable resource path
obfuscation and one to point to a path to output the path map to (for
later debugging).

Test: make aapt2_tests
Bug: b/75965637

Change-Id: I9cacafe1d17800d673566b2d61b0b88f3fb8d60c
diff --git a/tools/aapt2/optimize/ResourcePathShortener.h b/tools/aapt2/optimize/ResourcePathShortener.h
new file mode 100644
index 0000000..f1074ef
--- /dev/null
+++ b/tools/aapt2/optimize/ResourcePathShortener.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef AAPT_OPTIMIZE_RESOURCEPATHSHORTENER_H
+#define AAPT_OPTIMIZE_RESOURCEPATHSHORTENER_H
+
+#include <map>
+
+#include "android-base/macros.h"
+
+#include "process/IResourceTableConsumer.h"
+
+namespace aapt {
+
+class ResourceTable;
+
+// Maps resources in the apk to shortened paths.
+class ResourcePathShortener : public IResourceTableConsumer {
+ public:
+  explicit ResourcePathShortener(std::map<std::string, std::string>& path_map_out);
+
+  bool Consume(IAaptContext* context, ResourceTable* table) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ResourcePathShortener);
+  std::map<std::string, std::string>& path_map_;
+};
+
+} // namespace aapt
+
+#endif  // AAPT_OPTIMIZE_RESOURCEPATHSHORTENER_H