Clean up some redundant or otherwise suspect code

* java/org/gnu/emacs/EmacsOpenActivity.java (onCreate):
Don't check if URI is non-NULL, for instanceof checks this
also.

* java/org/gnu/emacs/EmacsSafThread.java (accessDocument1):
Don't check !writable twice.

* java/org/gnu/emacs/EmacsService.java (documentIdFromName):
Designate this function as public, since it is called
through JNI.

java/org/gnu/emacs/EmacsOpenActivity.java

@@ -533,8 +533,7 @@ private class EmacsClientThread extends Thread
 		else
 		  uri = intent.getParcelableExtra (Intent.EXTRA_STREAM);
 
-		if (uri != null
-		    && (scheme = uri.getScheme ()) != null
+		if ((scheme = uri.getScheme ()) != null
 		    && scheme.equals ("content"))
 		  {
 		    tem1 = EmacsService.buildContentName (uri);

java/org/gnu/emacs/EmacsSafThread.java

@@ -1430,9 +1430,6 @@ type is either NULL (in which case id should also be NULL) or
 	    /* If so, don't check for FLAG_SUPPORTS_WRITE.
 	       Check for FLAG_DIR_SUPPORTS_CREATE instead.  */
 
-	    if (!writable)
-	      return 0;
-
 	    index = cursor.getColumnIndex (Document.COLUMN_FLAGS);
 	    if (index < 0)
 	      return -3;

java/org/gnu/emacs/EmacsService.java

@@ -1413,7 +1413,7 @@ else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
      of OperationCanceledException, SecurityException,
      FileNotFoundException, or UnsupportedOperationException.  */
 
-  private int
+  public int
   documentIdFromName (String tree_uri, String name, String[] id_return)
   {
     /* Start the thread used to run SAF requests if it isn't already