core: Drop unused arguments to meta_display_grab_op()

Now that it is called from a single place, there's a few arguments
that are unnecessary:

- button and modifiers are unused
- already_grabbed was originally added to handle grab transitions between
  window menus (GtkMenus, back in the day) with display grabs. It's no
  longer necessary now
- frame_action can be passed through the META_GRAB_OP_WINDOW_FLAG UNCONSTRAINED
  flag

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2683>

src/core/display-private.h

@@ -162,7 +162,6 @@ struct _MetaDisplay
   /* current window operation */
   MetaGrabOp  grab_op;
   MetaWindow *grab_window;
-  int         grab_button;
   int         grab_anchor_root_x;
   int         grab_anchor_root_y;
   MetaRectangle grab_anchor_window_pos;
@@ -427,10 +426,6 @@ void meta_display_flush_queued_window (MetaDisplay   *display,
 gboolean meta_display_begin_grab_op (MetaDisplay *display,
                                      MetaWindow  *window,
                                      MetaGrabOp   op,
-                                     gboolean     pointer_already_grabbed,
-                                     gboolean     frame_action,
-                                     int          button,
-                                     gulong       modmask,
                                      uint32_t     timestamp,
                                      int          root_x,
                                      int          root_y);

src/core/display.c

@@ -1855,10 +1855,6 @@ gboolean
 meta_display_begin_grab_op (MetaDisplay *display,
                             MetaWindow  *window,
                             MetaGrabOp   op,
-                            gboolean     pointer_already_grabbed,
-                            gboolean     frame_action,
-                            int          button,
-                            gulong       modmask, /* XXX - ignored */
                             guint32      timestamp,
                             int          root_x,
                             int          root_y)
@@ -1870,8 +1866,8 @@ meta_display_begin_grab_op (MetaDisplay *display,
   g_assert (window != NULL);
 
   meta_topic (META_DEBUG_WINDOW_OPS,
-              "Doing grab op %u on window %s button %d pointer already grabbed: %d pointer pos %d,%d",
+              "Doing grab op %u on window %s pointer pos %d,%d",
-              op, window->desc, button, pointer_already_grabbed,
+              op, window->desc,
               root_x, root_y);
 
   if (display->grab_op != META_GRAB_OP_NONE)
@@ -1882,9 +1878,6 @@ meta_display_begin_grab_op (MetaDisplay *display,
       return FALSE;
     }
 
-  if (!frame_action)
-    op |= META_GRAB_OP_WINDOW_FLAG_UNCONSTRAINED;
-
   event_route = get_event_route_from_grab_op (op);
 
   if (event_route == META_EVENT_ROUTE_WINDOW_OP)
@@ -1912,9 +1905,6 @@ meta_display_begin_grab_op (MetaDisplay *display,
 
   display->grab_have_pointer = FALSE;
 
-  if (pointer_already_grabbed)
-    display->grab_have_pointer = TRUE;
-
   if (META_IS_BACKEND_X11 (backend_from_display (display)) &&
       display->x11_display)
     {
@@ -1954,7 +1944,6 @@ meta_display_begin_grab_op (MetaDisplay *display,
   display->event_route = event_route;
   display->grab_op = op;
   display->grab_window = grab_window;
-  display->grab_button = button;
   display->grab_tile_mode = grab_window->tile_mode;
   display->grab_tile_monitor_number = grab_window->tile_monitor_number;
   display->grab_anchor_root_x = root_x;
@@ -2043,7 +2032,6 @@ meta_display_end_grab_op (MetaDisplay *display,
 
   display->event_route = META_EVENT_ROUTE_NORMAL;
   display->grab_window = NULL;
-  display->grab_button = 0;
   display->grab_tile_mode = META_TILE_NONE;
   display->grab_tile_monitor_number = -1;
   display->grab_anchor_root_x = 0;

src/core/window.c

@@ -6756,13 +6756,12 @@ meta_window_begin_grab_op (MetaWindow *window,
       y = pos.y;
     }
 
+  if (!frame_action)
+    op |= META_GRAB_OP_WINDOW_FLAG_UNCONSTRAINED;
+
   return meta_display_begin_grab_op (window->display,
                                      window,
                                      op,
-                                     FALSE,
-                                     frame_action,
-                                     0 /* button */,
-                                     0,
                                      timestamp,
                                      x, y);
 }

src/x11/window-x11.c

@@ -3373,11 +3373,8 @@ meta_window_x11_client_message (MetaWindow *window,
               else if ((button_mask & (1 << 3)) != 0)
                 button = 3;
 
-              if (button != 0)
+              if (button == 0)
-                window->display->grab_button = button;
+                meta_display_end_grab_op (window->display, timestamp);
-              else
-                meta_display_end_grab_op (window->display,
-                                          timestamp);
             }
           else
             {