Communicate frame titles to the window manager on Android

* java/org/gnu/emacs/EmacsActivity.java (detachWindow)
(attachWindow): Call updateWmName.
(updateWmName): New function; transfer wm name from the window
attached to the task's description.

* java/org/gnu/emacs/EmacsWindow.java (EmacsWindow)
<wmName>: New field.
(setWmName): New function.

* src/android.c (android_init_emacs_window): Link to new
function.
(android_set_wm_name): New function.

* src/android.h (struct android_emacs_service): Delete unused
entries.

* src/androidfns.c (android_set_name_internal, android_set_name)
(android_implicitly_set_name, android_explicitly_set_name)
(android_set_title): Port from X.

* src/androidterm.c (android_term_init): Compute default frame
title.

* src/androidterm.h (struct android_display_info) <x_id_name>:
New field.

2 files changed, 69 insertions, 1 deletions

diff --git a/java/org/gnu/emacs/EmacsActivity.java b/java/org/gnu/emacs/EmacsActivity.java
index 118c3375ad5..7d02e4f4834 100644
--- a/java/org/gnu/emacs/EmacsActivity.java
+++ b/java/org/gnu/emacs/EmacsActivity.java
@@ -27,6 +27,7 @@ import java.util.ArrayList;
 import java.util.concurrent.TimeUnit;
 
 import android.app.Activity;
+import android.app.ActivityManager.TaskDescription;
 
 import android.content.ContentResolver;
 import android.content.Context;
@@ -166,6 +167,10 @@ public class EmacsActivity extends Activity
         layout.removeView (window.view);
         window = null;
 
+        /* Reset the WM name.  */
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
+          updateWmName ();
+
         invalidateFocus (0);
       }
   }
@@ -205,6 +210,11 @@ public class EmacsActivity extends Activity
           invalidateFocus (1);
         }
       });
+
+    /* Synchronize the window's window manager name with this activity's
+       task in the recents list.  */
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
+      updateWmName ();
   }
 
   @Override
@@ -522,6 +532,29 @@ public class EmacsActivity extends Activity
       }
   }
 
+  /* Update the name of this activity's task description from the
+     current window, or reset the same if no window is attached.  */
+
+  @SuppressWarnings ("deprecation")
+  public final void
+  updateWmName ()
+  {
+    String wmName;
+    TaskDescription description;
+
+    if (window == null || window.wmName == null)
+      wmName = "Emacs";
+    else
+      wmName = window.wmName;
+
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.TIRAMISU)
+      description = new TaskDescription (wmName);
+    else
+      description = (new TaskDescription.Builder ()
+                     .setLabel (wmName).build ());
+    setTaskDescription (description);
+  }
+
   @Override
   public final void
   onAttachedToWindow ()
diff --git a/java/org/gnu/emacs/EmacsWindow.java b/java/org/gnu/emacs/EmacsWindow.java
index f8dd8518af0..483ba0dbced 100644
--- a/java/org/gnu/emacs/EmacsWindow.java
+++ b/java/org/gnu/emacs/EmacsWindow.java
@@ -169,6 +169,11 @@ public final class EmacsWindow extends EmacsHandleObject
      and whether this window has previously been attached to a task.  */
   public boolean preserve, previouslyAttached;
 
+  /* The window manager name of this window, which supplies the name of
+     activities in which it is displayed as a toplevel window, or
+     NULL.  */
+  public String wmName;
+
   public
   EmacsWindow (final EmacsWindow parent, int x, int y,
                int width, int height, boolean overrideRedirect)
@@ -1562,6 +1567,36 @@ public final class EmacsWindow extends EmacsHandleObject
     return dontFocusOnMap;
   }
 
+  public void
+  setWmName (final String wmName)
+  {
+    if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP)
+      return;
+
+    EmacsService.SERVICE.runOnUiThread (new Runnable () {
+        @Override
+        public void
+        run ()
+        {
+          EmacsActivity activity;
+          Object tem;
+
+          EmacsWindow.this.wmName = wmName;
+
+          /* If an activity is already attached, replace its task
+             description.  */
+
+          tem = getAttachedConsumer ();
+
+          if (tem != null && tem instanceof EmacsActivity)
+            {
+              activity = (EmacsActivity) tem;
+              activity.updateWmName ();
+            }
+        }
+      });
+  }
+
   public int[]
   translateCoordinates (int x, int y)
   {
@@ -1631,7 +1666,7 @@ public final class EmacsWindow extends EmacsHandleObject
           fullscreen = isFullscreen;
           tem = getAttachedConsumer ();
 
-          if (tem != null)
+          if (tem != null && tem instanceof EmacsActivity)
             {
               activity = (EmacsActivity) tem;
               activity.syncFullscreenWith (EmacsWindow.this);