Add PerformActionCallback to views::Combobox

This makes views::Combobox use a base::RepeatingCallback internally.
Pre-existing uses of ComboboxListener are wrapped in a callback in
set_listener(). Cleanups removing ComboboxListeners will follow.

Bug: 772945
Change-Id: I2c1b4a7637ba5125fd7774e1f18f4751ced9959c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2401951
Commit-Queue: Peter Boström <pbos@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Auto-Submit: Peter Boström <pbos@chromium.org>
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805493}

ui/views/controls/combobox/combobox.cc

@@ -30,7 +30,6 @@
 #include "ui/views/background.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/controls/button/button_controller.h"
-#include "ui/views/controls/combobox/combobox_listener.h"
 #include "ui/views/controls/combobox/combobox_util.h"
 #include "ui/views/controls/combobox/empty_combobox_model.h"
 #include "ui/views/controls/focus_ring.h"
@@ -677,10 +676,9 @@ void Combobox::OnPerformAction() {
   NotifyAccessibilityEvent(ax::mojom::Event::kValueChanged, true);
   SchedulePaint();
 
-  if (listener_)
-    listener_->OnPerformAction(this);
+  callback_.Run();
 
-  // Note |this| may be deleted by |listener_|.
+  // Note |this| may be deleted by |callback_|.
 }
 
 gfx::Size Combobox::GetContentSize() const {

ui/views/controls/combobox/combobox.h

@@ -6,6 +6,7 @@
 #define UI_VIEWS_CONTROLS_COMBOBOX_COMBOBOX_H_
 
 #include <memory>
+#include <utility>
 
 #include "base/macros.h"
 #include "base/scoped_observer.h"
@@ -14,6 +15,7 @@
 #include "ui/base/models/combobox_model.h"
 #include "ui/base/models/combobox_model_observer.h"
 #include "ui/views/controls/button/button.h"
+#include "ui/views/controls/combobox/combobox_listener.h"
 #include "ui/views/controls/prefix_delegate.h"
 #include "ui/views/style/typography.h"
 
@@ -30,7 +32,6 @@ namespace test {
 class ComboboxTestApi;
 }
 
-class ComboboxListener;
 class FocusRing;
 class MenuRunner;
 class PrefixSelector;
@@ -44,6 +45,8 @@ class VIEWS_EXPORT Combobox : public View,
  public:
   METADATA_HEADER(Combobox);
 
+  using PerformActionCallback = base::RepeatingClosure;
+
   static constexpr int kDefaultComboboxTextContext = style::CONTEXT_BUTTON;
   static constexpr int kDefaultComboboxTextStyle = style::STYLE_PRIMARY;
 
@@ -63,8 +66,24 @@ class VIEWS_EXPORT Combobox : public View,
 
   const gfx::FontList& GetFontList() const;
 
-  // Sets the listener which will be called when a selection has been made.
-  void set_listener(ComboboxListener* listener) { listener_ = listener; }
+  // TODO(pbos): Migrate users of this to set_callback().
+  void set_listener(ComboboxListener* listener) {
+    if (!listener) {
+      set_callback(base::DoNothing());
+      return;
+    }
+
+    set_callback(base::BindRepeating(
+        [](ComboboxListener* listener, Combobox* combobox) {
+          listener->OnPerformAction(combobox);
+        },
+        listener, this));
+  }
+
+  // Sets the callback which will be called when a selection has been made.
+  void set_callback(PerformActionCallback callback) {
+    callback_ = std::move(callback);
+  }
 
   // Gets/Sets the selected index.
   int GetSelectedIndex() const { return selected_index_; }
@@ -170,8 +189,8 @@ class VIEWS_EXPORT Combobox : public View,
   // in the drop-down menu.
   const int text_style_;
 
-  // Our listener. Not owned. Notified when the selected index change.
-  ComboboxListener* listener_ = nullptr;
+  // Callback notified when the selected index changes.
+  PerformActionCallback callback_ = base::DoNothing();
 
   // The current selected index; -1 and means no selection.
   int selected_index_ = -1;