Enlarge size of touch target for several location bar buttons without affecting visual layout.

chrome/browser/ui/views/location_bar/touchable_location_bar_view.h

+// Copyright (c) 2012 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_LOCATION_BAR_TOUCHABLE_LOCATION_BAR_VIEW_H_
+#define CHROME_BROWSER_UI_VIEWS_LOCATION_BAR_TOUCHABLE_LOCATION_BAR_VIEW_H_
+#pragma once
+
+// To make your location bar View named FooBlat extend itself into the
+// padding around it to get an enlarged touch target, inherit from
+// TouchableLocationBarView<FooBlat> and call
+// TouchableLocationBarViewBase::Init() from your constructor.
+
+#include "ui/views/border.h"
+
+class TouchableLocationBarViewBase {

[Peter Kasting, 2012/06/12 22:03:52]

I don't understand what splitting this class in two buys you.

It seems like making this class be the templated TouchableLocationBarView (and
rolling the bits of that class into this one) would work fine.

[Jói, 2012/06/13 11:29:39]

Rolled it into one class as requested.  This simplified things down to two
methods.

+ public:
+  // Call this from the constructor (or during early initialization)
+  // of a class that inherits from TouchableLocationBarView<>.
+  void Init();
+
+  // Returns the number of pixels of built-in padding to the left and
+  // right of the image for this view.
+  int GetBuiltInHorizontalPadding() const;
+
+ protected:
+  int touch_horizontal_padding() const;

[Peter Kasting, 2012/06/12 22:03:52]

Nit: Should be camel-cased since implementation is not a simple inline getter

[Jói, 2012/06/13 11:29:39]

This method went away with the simplification.

+  virtual void SetBorder(int vertical_padding, int horizontal_padding) = 0;
+};
+
+// A mix-in for a class based on views::View and intended for the
+// location bar.  In a touch layout, the mix-in adds an empty border
+// around the view to increase the size of the touch target.  The
+// border extends a few pixels up and down, which doesn't affect
+// layout, and extends half of the padding used between items in the
+// location bar to the left and right.
+template<class Concrete>
+class TouchableLocationBarView : public TouchableLocationBarViewBase {
+ private:
+  virtual void SetBorder(int vertical_padding, int horizontal_padding) OVERRIDE;
+};
+
+template<class Concrete>
+void TouchableLocationBarView<Concrete>::SetBorder(int vertical_padding,
+                                                   int horizontal_padding) {
+  static_cast<Concrete*>(this)->set_border(views::Border::CreateEmptyBorder(
+      vertical_padding, horizontal_padding,
+      vertical_padding, horizontal_padding));
+}
+
+#endif  // CHROME_BROWSER_UI_VIEWS_LOCATION_BAR_TOUCHABLE_LOCATION_BAR_VIEW_H_