Guarantee files are auto-saved when Emacs is terminated by Android

* java/org/gnu/emacs/EmacsNative.java (shutDownEmacs):

* java/org/gnu/emacs/EmacsService.java (onDestroy): New
function.  When invoked, call shut_down_emacs and await its
completion.

* src/android.c (android_shut_down_emacs, shutDownEmacs): New
functions.

java/org/gnu/emacs/EmacsNative.java

@@ -92,6 +92,10 @@ public static native void setEmacsParams (AssetManager assetManager,
      loadup.el itself.  */
   public static native void initEmacs (String argv[], String dumpFile);
 
+  /* Call shut_down_emacs to auto-save and unlock files in the main
+     thread, then return.  */
+  public static native void shutDownEmacs ();
+
   /* Abort and generate a native core dump.  */
   public static native void emacsAbort ();
 

java/org/gnu/emacs/EmacsService.java

@@ -321,6 +321,18 @@ invocation of app_process (through android-emacs) can
       }
   }
 
+  @Override
+  public void
+  onDestroy ()
+  {
+    /* This function is called immediately before the system kills
+       Emacs.  In this respect, it is rather akin to a SIGDANGER
+       signal, so force an auto-save accordingly.  */
+
+    EmacsNative.shutDownEmacs ();
+    super.onDestroy ();
+  }
+
 
 
   /* Functions from here on must only be called from the Emacs

src/android.c

@@ -1938,6 +1938,25 @@ NATIVE_NAME (quit) (JNIEnv *env, jobject object)
   kill (getpid (), SIGIO);
 }
 
+/* Call shut_down_emacs subsequent to a call to the service's
+   onDestroy callback.  CLOSURE is ignored.  */
+
+static void
+android_shut_down_emacs (void *closure)
+{
+  __android_log_print (ANDROID_LOG_INFO, __func__,
+		       "The Emacs service is being shut down");
+  shut_down_emacs (0, Qnil);
+}
+
+JNIEXPORT void JNICALL
+NATIVE_NAME (shutDownEmacs) (JNIEnv *env, jobject object)
+{
+  JNI_STACK_ALIGNMENT_PROLOGUE;
+
+  android_run_in_emacs_thread (android_shut_down_emacs, NULL);
+}
+
 JNIEXPORT jlong JNICALL
 NATIVE_NAME (sendConfigureNotify) (JNIEnv *env, jobject object,
 				   jshort window, jlong time,