expose platform-native monitor identifier

src/android/mod.rs

@@ -14,6 +14,7 @@ use std::collections::VecDeque;
 use Api;
 use BuilderAttribs;
 use GlRequest;
+use NativeMonitorID;
 
 pub struct Window {
     display: ffi::egl::types::EGLDisplay,
@@ -41,6 +42,10 @@ impl MonitorID {
         Some("Primary".to_string())
     }
 
+    pub fn get_native_identifier(&self) -> NativeMonitorID {
+        NativeMonitorID::Unavailable
+    }
+
     pub fn get_dimensions(&self) -> (u32, u32) {
         unimplemented!()
     }