[Base] Android content URI file memory mapping

src/xenia/base/mapped_memory.h

@@ -12,7 +12,9 @@
 
 #include <filesystem>
 #include <memory>
-#include <string>
+#include <string_view>
+
+#include "xenia/base/platform.h"
 
 namespace xe {
 
@@ -26,21 +28,25 @@ class MappedMemory {
   static std::unique_ptr<MappedMemory> Open(const std::filesystem::path& path,
                                             Mode mode, size_t offset = 0,
                                             size_t length = 0);
+#if XE_PLATFORM_ANDROID
+  static std::unique_ptr<MappedMemory> OpenForAndroidContentUri(
+      const std::string_view uri, Mode mode, size_t offset = 0,
+      size_t length = 0);
+#endif  // XE_PLATFORM_ANDROID
 
-  MappedMemory(const std::filesystem::path& path, Mode mode)
-      : path_(path), mode_(mode), data_(nullptr), size_(0) {}
-  MappedMemory(const std::filesystem::path& path, Mode mode, void* data,
-               size_t size)
-      : path_(path), mode_(mode), data_(data), size_(size) {}
+  MappedMemory() : data_(nullptr), size_(0) {}
+  MappedMemory(void* data, size_t size) : data_(data), size_(size) {}
   MappedMemory(const MappedMemory& mapped_memory) = delete;
   MappedMemory& operator=(const MappedMemory& mapped_memory) = delete;
   MappedMemory(MappedMemory&& mapped_memory) = delete;
   MappedMemory& operator=(MappedMemory&& mapped_memory) = delete;
   virtual ~MappedMemory() = default;
 
-  std::unique_ptr<MappedMemory> Slice(Mode mode, size_t offset, size_t length) {
+  // The mapping is still backed by the object the slice was created from, a
+  // slice is not owning.
+  std::unique_ptr<MappedMemory> Slice(size_t offset, size_t length) {
     return std::unique_ptr<MappedMemory>(
-        new MappedMemory(path_, mode, data() + offset, length));
+        new MappedMemory(data() + offset, length));
   }
 
   uint8_t* data() const { return reinterpret_cast<uint8_t*>(data_); }
@@ -54,8 +60,6 @@ class MappedMemory {
   virtual bool Remap(size_t offset, size_t length) { return false; }
 
  protected:
-  std::filesystem::path path_;
-  Mode mode_;
   void* data_;
   size_t size_;
 };