Prevent crashes and related issues if initial activity is destroyed on Android

* java/org/gnu/emacs/EmacsWindow.java
(EmacsWindow) <initialWindowCreated>: New variable.
(EmacsWindow): If the initial frame has not yet been created,
set attachmentToken to -1.

* java/org/gnu/emacs/EmacsWindowManager.java (registerWindow):
When the window's attachment token is -1 (i.e., it is the
default window), start EmacsActivity rather than
EmacsMultitaskActivity.  Catch exceptions around startActivity.

java/org/gnu/emacs/EmacsWindow.java

@@ -74,6 +74,9 @@ public final class EmacsWindow extends EmacsHandleObject
 {
   private static final String TAG = "EmacsWindow";
 
+  /* Whether any windows have yet been created in this session.  */
+  private static boolean initialWindowCreated;
+
   private static class Coordinate
   {
     /* Integral coordinate.  */
@@ -192,6 +195,14 @@ public final class EmacsWindow extends EmacsHandleObject
     this.parent = parent;
     this.overrideRedirect = overrideRedirect;
 
+    /* The initial frame should always be bound to the startup
+       activity.  */
+    if (!initialWindowCreated)
+      {
+	this.attachmentToken = -1;
+        initialWindowCreated = true;
+      }
+
     /* Create the list of children.  */
     children = new ArrayList<EmacsWindow> ();
 

java/org/gnu/emacs/EmacsWindowManager.java

@@ -174,6 +174,27 @@ public final class EmacsWindowManager
 	  }
       }
 
+    /* Do not create a multitasking activity for the initial frame,
+       but arrange to start EmacsActivity.  */
+    if (window.attachmentToken == -1)
+      {
+	intent = new Intent (EmacsService.SERVICE,
+			     EmacsActivity.class);
+	intent.addFlags (Intent.FLAG_ACTIVITY_NEW_TASK);
+
+	try
+	  {
+	    EmacsService.SERVICE.startActivity (intent);
+	  }
+	catch (Exception e)
+	  {
+	    Log.w (TAG, "an activity could not be started on behalf"
+		   + " of the mapped default window " + window.handle);
+	  }
+
+	return;
+      }
+
     intent = new Intent (EmacsService.SERVICE,
 			 EmacsMultitaskActivity.class);
 
@@ -205,6 +226,8 @@ public final class EmacsWindowManager
     window.attachmentToken = token;
     intent.putExtra (ACTIVITY_TOKEN, token);
 
+    try
+      {
 	if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N)
 	  EmacsService.SERVICE.startActivity (intent);
 	else
@@ -214,6 +237,12 @@ public final class EmacsWindowManager
 	    options.setLaunchBounds (window.getGeometry ());
 	    EmacsService.SERVICE.startActivity (intent, options.toBundle ());
 	  }
+      }
+    catch (Exception e)
+      {
+	Log.w (TAG, "an activity could not be started on behalf"
+	       + " of a mapped window, " + window.handle);
+      }
 
     pruneWindows ();
   }