views: add layout delegates

chrome/browser/ui/views/harmony/layout_delegate.h

+// Copyright 2016 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_HARMONY_LAYOUT_DELEGATE_H_
+#define CHROME_BROWSER_UI_VIEWS_HARMONY_LAYOUT_DELEGATE_H_
+
+#include "ui/views/layout/grid_layout.h"
+
+class LayoutDelegate {
+ public:
+  enum class LayoutDistanceType {
+    PANEL_VERT_MARGIN,
+    RELATED_CONTROL_HORIZONTAL_SPACING,
+    RELATED_CONTROL_VERTICAL_SPACING,
+    RELATED_BUTTON_HORIZONTAL_SPACING,
+    UNRELATED_CONTROL_VERTICAL_SPACING,
+    UNRELATED_CONTROL_LARGE_VERTICAL_SPACING,
+    BUTTON_HEDGE_MARGIN_NEW,
+    BUTTON_VEDGE_MARGIN_NEW,
+  };
+
+  LayoutDelegate() {}
+  virtual ~LayoutDelegate() {}
+
+  // Returns the active LayoutDelegate singleton, depending on UI configuration.
+  // By default, this is the same instance returned by Get(), but if Harmony
+  // or another UI style is enabled, this may be an instance of a LayoutDelegate
+  // subclass instead.
+  static LayoutDelegate* Get();
+
+  // Returns a layout distance, indexed by |type|. These distances are in
+  // device-independent units.
+  virtual int GetLayoutDistance(LayoutDistanceType type) const;
+
+  // Returns the alignment used for control labels in a GridLayout; for example,
+  // in this GridLayout:
+  //   ---------------------------
+  //   | Label 1      Checkbox 1 |
+  //   | Label 2      Checkbox 2 |
+  //   ---------------------------
+  // This value controls the alignment used for "Label 1" and "Label 2".
+  virtual views::GridLayout::Alignment GetControlLabelGridAlignment() const;
+
+  // Returns whether to use extra padding on dialogs. If this is false, content
+  // Views for dialogs should not insert extra padding at their own edges.
+  virtual bool UseExtraDialogPadding() const;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(LayoutDelegate);
+};
+
+#endif  // CHROME_BROWSER_UI_VIEWS_HARMONY_LAYOUT_DELEGATE_H_