Introduce tui_win_info::clear_detail method

This introduces the clear_detail method and updates the various
subclasses of tui_win_info to implement it.  A subsequent patch will
remove tui_clear_win_detail, but that isn't done for now because at
this point it isn't readily obvious that the NULL check is not needed.

gdb/ChangeLog
2019-06-25  Tom Tromey  <tom@tromey.com>

	* tui/tui-data.h (struct tui_win_info, struct tui_source_window)
	(struct tui_data_window, struct tui_cmd_window): Declare
	clear_detail method.
	* tui/tui-data.c (tui_source_window::clear_detail)
	(tui_cmd_window::clear_detail, tui_data_window::clear_detail): New
	methods.
	(tui_clear_win_detail): Simplify.

1 files changed, 9 insertions, 0 deletions

diff --git a/gdb/tui/tui-data.h b/gdb/tui/tui-data.h
index 1627625..5006604 100644
--- a/gdb/tui/tui-data.h
+++ b/gdb/tui/tui-data.h
@@ -280,6 +280,9 @@ public:
 
   virtual ~tui_win_info ();
 
+  /* Clear the pertinent detail in the window.  */
+  virtual void clear_detail () = 0;
+
   struct tui_gen_win_info generic;	/* General window information.  */
   union
   {
@@ -300,18 +303,24 @@ struct tui_source_window : public tui_win_info
 {
   explicit tui_source_window (enum tui_win_type type);
   DISABLE_COPY_AND_ASSIGN (tui_source_window);
+
+  void clear_detail () override;
 };
 
 struct tui_data_window : public tui_win_info
 {
   tui_data_window ();
   DISABLE_COPY_AND_ASSIGN (tui_data_window);
+
+  void clear_detail () override;
 };
 
 struct tui_cmd_window : public tui_win_info
 {
   tui_cmd_window ();
   DISABLE_COPY_AND_ASSIGN (tui_cmd_window);
+
+  void clear_detail () override;
 };
 
 extern int tui_win_is_source_type (enum tui_win_type win_type);