Merge "Implement Send trait for Binder<T>" am: a7e3f1d7

/// the AIDL backend, users need only implement the high-level AIDL-defined

/// interface. The AIDL compiler then generates a container struct that wraps

/// the user-defined service and implements `Remotable`.

pub trait Remotable: Sync {

pub trait Remotable: Send + Sync {

    /// The Binder interface descriptor string.

    ///

    /// This string is a unique identifier for a Binder interface, and should be

    rust_object: *mut T,

}

/// # Safety

///

/// A `Binder<T>` is a pair of unique owning pointers to two values:

///   * a C++ ABBinder which the C++ API guarantees can be passed between threads

///   * a Rust object which implements `Remotable`; this trait requires `Send + Sync`

///

/// Both pointers are unique (never escape the `Binder<T>` object and are not copied)

/// so we can essentially treat `Binder<T>` as a box-like containing the two objects;

/// the box-like object inherits `Send` from the two inner values, similarly

/// to how `Box<T>` is `Send` if `T` is `Send`.

unsafe impl<T: Remotable> Send for Binder<T> {}

impl<T: Remotable> Binder<T> {

    /// Create a new Binder remotable object.

    ///