[Toolbar] Base toolbar button class with background images for button states

chrome/browser/ui/views/toolbar/back_button.cc

+// Copyright 2013 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.
+
+#include "chrome/browser/ui/views/toolbar/back_button.h"
+
+#include "ui/views/controls/button/label_button_border.h"
+#include "ui/views/focus_border.h"
+
+BackButton::BackButton(views::ButtonListener* listener,
+                       ui::MenuModel* model)
+    : ToolbarButton(listener, model),
+      margin_leading_(0) {
+}
+
+BackButton::~BackButton() {
+}
+
+gfx::Rect BackButton::GetThemePaintRect() const  {
+  gfx::Rect rect(LabelButton::GetThemePaintRect());
+  rect.Inset(margin_leading_, 0, 0, 0);
+  return rect;
+}
+
+void BackButton::SetLeadingMargin(int margin) {
+  // Adjust border insets to follow the margin change,
+  // which will be reflected in where the border is painted
+  // through |GetThemePaintRect|.
+  gfx::Insets insets(border()->GetInsets());
+  static_cast<views::LabelButtonBorder*>(border())->set_insets(
+      gfx::Insets(insets.top(), insets.left() + margin - margin_leading_,
+                  insets.bottom(), insets.right()));
+
+  // Similarly fiddle the focus border. Value consistent with LabelButton
+  // and TextButton.
+  // TODO(gbillock): Refactor this magic number somewhere global to views,
+  // probably a FocusBorder constant.
+  const int kFocusRectInset = 3;
+  set_focus_border(views::FocusBorder::CreateDashedFocusBorder(
+      kFocusRectInset + margin, kFocusRectInset,
+      kFocusRectInset, kFocusRectInset));
+
+  margin_leading_ = margin;
+  InvalidateLayout();
+}