Broke out layout metric information from ViewsDelegate to LayoutProvider

ui/views/layout/views_layout_delegate.h

+// Copyright 2017 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 UI_VIEWS_LAYOUT_VIEWS_LAYOUT_DELEGATE_H_
+#define UI_VIEWS_LAYOUT_VIEWS_LAYOUT_DELEGATE_H_
+
+#include "base/macros.h"
+#include "ui/gfx/geometry/insets.h"
+#include "ui/views/style/typography_provider.h"
+#include "ui/views/views_export.h"
+
+namespace views {
+
+enum InsetsMetric {
+  // The margins that should be applied around a bubble dialog.
+  BUBBLE_DIALOG,
+  // The insets that should be applied around a DialogClientView. Note that
+  // the top inset is used for the distance between the buttons and the
+  // DialogClientView's content view.
+  DIALOG_BUTTON,
+  // The insets that should be applied around a dialog's frame view.
+  DIALOG_FRAME_VIEW,
+  // Padding to add to vector image buttons to increase their click and touch
+  // target size.
+  VECTOR_IMAGE_BUTTON,
+};
+
+enum DistanceMetric {
+  // The default padding to add on each side of a button's label.
+  BUTTON_HORIZONTAL_PADDING,
+  // The distance between a dialog's edge and the close button in the upper
+  // trailing corner.
+  CLOSE_BUTTON_MARGIN,
+  // The default minimum width of a dialog button.
+  DIALOG_BUTTON_MINIMUM_WIDTH,
+  // The spacing between a pair of related horizontal buttons, used for
+  // dialog layout.
+  RELATED_BUTTON_HORIZONTAL,
+  // Horizontal spacing between controls that are logically related.
+  RELATED_CONTROL_HORIZONTAL,
+  // The spacing between a pair of related vertical controls, used for
+  // dialog layout.
+  RELATED_CONTROL_VERTICAL,
+};
+
+class VIEWS_EXPORT ViewsLayoutDelegate {

[Peter Kasting, 2017/04/04 02:08:56]

Can we just call this LayoutDelegate, and call the subclasses
ChromeLayoutDelegate and HarmonyLayoutDelegate?

I don't see what having "Views" in all three class names buys us, especially
when users of this class already preface with views::.

[kylix_rd, 2017/04/04 20:28:23]

Now that the original LayoutDelegate and HarmonyLayoutDelegate classes are gone,
this makes sense.

+ public:
+  ViewsLayoutDelegate();
+  virtual ~ViewsLayoutDelegate();
+
+  static ViewsLayoutDelegate* Get();
+
+  // Returns the insets metric according to the given enumeration element.
+  virtual gfx::Insets GetInsetsMetric(InsetsMetric metric) const;
+
+  // Returns the distance metric between elements according to the given
+  // enumeration element.

[Peter Kasting, 2017/04/04 02:08:56]

Nit: "Returns the distance for the given metric"?  Similarly above "Returns the
insets for the given metric"?

Basically, I don't like saying "between elements" here since not all distances
are between elements, and I don't like either of the comment saying they return
an "XXX metric" since that's the name of the identifying enum rather than the
actual thing-being-returned-itself.

[kylix_rd, 2017/04/04 20:28:23]

Done.
 
What about "edge(s)"? That is, essentially, what the distances are between. For
width/height, it is between the top/bottom or left/right edges. Between
controls, it would be the top edge of one to the bottom edge of another.

[Peter Kasting, 2017/04/05 19:30:10]

It seems at best unnecessary to me, but if you feel it improves things, go for
it.

+  virtual int GetDistanceMetric(DistanceMetric metric) const;
+
+  // Returns the TypographyProvider, used to configure text properties such as
+  // font, weight, color, size, and line height. Never null.
+  virtual const TypographyProvider& GetTypographyProvider() const;
+
+ private:
+  DefaultTypographyProvider typography_provider_;

[Peter Kasting, 2017/04/04 02:08:56]

Seems like this should be a static local in GetTypographyProvider() to avoid
subclasses inheriting it.

[kylix_rd, 2017/04/04 20:28:23]

OK. I just moved the implementation from ViewsDelegate.

+
+  DISALLOW_COPY_AND_ASSIGN(ViewsLayoutDelegate);
+};
+
+}  // namespace views
+
+#endif  // CHROME_BROWSER_UI_VIEWS_HARMONY_LAYOUT_DELEGATE_H_