app: plumbing for physical android key events

This is only the first half of physical key event mapping. The
modifiers and hardware key codes will be in a followup CL. I'm
splitting this out because it covers two other parts of the problem:
first is maintaining a JNIEnv pointer for the main routine, the
second is access to the Android unicode key map. The NDK does not have
a method to give us the key mapping, so we get to it via
GoNativeActivity.

Tested with a USB keyboard. I'll attempt an abd-based unit test later,
but I suspect it will be difficult to set a device ID.

Change-Id: Ie93700d1f2a5d382a9b17cdd668cb4acaa6e4bcc
Reviewed-on: https://go-review.googlesource.com/13649
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>

app/GoNativeActivity.java

@@ -7,6 +7,7 @@ import android.content.pm.ActivityInfo;
 import android.content.pm.PackageManager;
 import android.os.Bundle;
 import android.util.Log;
+import android.view.KeyCharacterMap;
 
 public class GoNativeActivity extends NativeActivity {
 	private static GoNativeActivity goNativeActivity;
@@ -20,6 +21,21 @@ public class GoNativeActivity extends NativeActivity {
 		return getCacheDir().getAbsolutePath();
 	}
 
+	int getRune(int deviceId, int keyCode, int metaState) {
+		try {
+			int rune = KeyCharacterMap.load(deviceId).get(keyCode, metaState);
+			if (rune == 0) {
+				return -1;
+			}
+			return rune;
+		} catch (KeyCharacterMap.UnavailableException e) {
+			return -1;
+		} catch (Exception e) {
+			Log.e("Go", "exception reading KeyCharacterMap", e);
+			return -1;
+		}
+	}
+
 	private void load() {
 		// Interestingly, NativeActivity uses a different method
 		// to find native code to execute, avoiding