Merge "Add SharedMemory.fromFileDescriptor" am: d0792368

    method public void close();

    method @NonNull public static android.os.SharedMemory create(@Nullable String, int) throws android.system.ErrnoException;

    method public int describeContents();

    method @NonNull public static android.os.SharedMemory fromFileDescriptor(@NonNull android.os.ParcelFileDescriptor);

    method public int getSize();

    method @NonNull public java.nio.ByteBuffer map(int, int, int) throws android.system.ErrnoException;

    method @NonNull public java.nio.ByteBuffer mapReadOnly() throws android.system.ErrnoException;

        }

    }

    /**

     * Creates an instance from existing shared memory passed as {@link ParcelFileDescriptor}.

     *

     * <p> The {@code fd} should be a shared memory created from

       {@code SharedMemory or ASharedMemory}. This can be useful when shared memory is passed as

       file descriptor through JNI or binder service implemented in cpp.

     * <p> Note that newly created {@code SharedMemory} takes ownership of passed {@code fd} and

     * the original {@code fd} becomes detached (Check {@link ParcelFileDescriptor#detachFd()}).

     * If the caller wants to use the file descriptor after the call, the caller should duplicate

     * the file descriptor (Check {@link ParcelFileDescriptor#dup()}) and pass the duped version

     * instead.

     *

     * @param fd File descriptor of shared memory passed as {@link ParcelFileDescriptor}.

     */

    public static @NonNull SharedMemory fromFileDescriptor(@NonNull ParcelFileDescriptor fd) {

        FileDescriptor f = new FileDescriptor();

        f.setInt$(fd.detachFd());

        return new SharedMemory(f);

    }

    private static final int PROT_MASK = OsConstants.PROT_READ | OsConstants.PROT_WRITE

            | OsConstants.PROT_EXEC | OsConstants.PROT_NONE;