Elf interface for new unwinder.

This cl includes the code to read arm unwind information from a shared
library.

Bug: 23762183

Test: Passes all unit tests. I can dump the arm unwind information
Test: for an arm shared library.
Change-Id: I43501ea2eab843b81de8bd5128401dd1971af8d3
diff --git a/libunwindstack/MapInfo.h b/libunwindstack/MapInfo.h
new file mode 100644
index 0000000..8342904
--- /dev/null
+++ b/libunwindstack/MapInfo.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2016 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 _LIBUNWINDSTACK_MAP_INFO_H
+#define _LIBUNWINDSTACK_MAP_INFO_H
+
+#include <stdint.h>
+
+#include <string>
+
+// Forward declarations.
+class Elf;
+class Memory;
+
+struct MapInfo {
+  uint64_t start;
+  uint64_t end;
+  uint64_t offset;
+  uint16_t flags;
+  std::string name;
+  Elf* elf = nullptr;
+  // This value is only non-zero if the offset is non-zero but there is
+  // no elf signature found at that offset. This indicates that the
+  // entire file is represented by the Memory object returned by CreateMemory,
+  // instead of a portion of the file.
+  uint64_t elf_offset;
+
+  Memory* CreateMemory(pid_t pid);
+};
+
+#endif  // _LIBUNWINDSTACK_MAP_INFO_H