[MD] Share button code between find bar and download shelf

chrome/browser/ui/views/bar_control_button.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_UI_VIEWS_BAR_CONTROL_BUTTON_H_
+#define CHROME_BROWSER_UI_VIEWS_BAR_CONTROL_BUTTON_H_
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "ui/views/animation/ink_drop_host.h"
+#include "ui/views/controls/button/image_button.h"
+
+namespace gfx {
+enum class VectorIconId;
+}
+
+namespace views {
+class InkDropAnimationController;
+}
+
+// A class for buttons that control bars (find bar, download shelf, etc.). The
+// button has an image and no text.
+class BarControlButton : public views::ImageButton, public views::InkDropHost {
+ public:
+  explicit BarControlButton(views::ButtonListener* listener);
+  ~BarControlButton() override;
+
+  // Sets the icon to display and provides a callback which should return the
+  // text color from which to derive this icon's color.
+  void SetIcon(gfx::VectorIconId id,
+               const base::Callback<SkColor(void)>& get_text_color_callback);

[sky, 2015/11/03 23:46:43]

It seems like all owners of this class are also themselves views that could just
as well override OnThemeChanged and call some function when the theme changes
with the color. Seems simpler than having the callback.

[Evan Stade, 2015/11/03 23:51:17]

The reason I went with the callback is that it's impossible to forget. This way,
BarControlButtons are always compelled to be theme-aware.

+
+  // views::ImageButton:
+  void OnThemeChanged() override;
+  void OnNativeThemeChanged(const ui::NativeTheme* theme) override;
+  void Layout() override;
+  bool OnMousePressed(const ui::MouseEvent& event) override;
+  void OnGestureEvent(ui::GestureEvent* event) override;
+  void OnMouseReleased(const ui::MouseEvent& event) override;
+  void NotifyClick(const ui::Event& event) override;
+
+ private:
+  // views::InkDropHost:
+  void AddInkDropLayer(ui::Layer* ink_drop_layer) override;
+  void RemoveInkDropLayer(ui::Layer* ink_drop_layer) override;
+
+  gfx::VectorIconId id_;
+  base::Callback<SkColor(void)> get_text_color_callback_;
+
+  // Animation controller for the ink drop ripple effect.
+  scoped_ptr<views::InkDropAnimationController> ink_drop_animation_controller_;
+
+  DISALLOW_COPY_AND_ASSIGN(BarControlButton);
+};
+
+#endif  // CHROME_BROWSER_UI_VIEWS_BAR_CONTROL_BUTTON_H_