Restored Pre-Harmony Bubble title margin metrics

ui/views/layout/layout_provider.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_LAYOUT_PROVIDER_H_
 #define UI_VIEWS_LAYOUT_LAYOUT_PROVIDER_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 {
   // Embedders can extend this enum with additional values that are understood
   // by the LayoutProvider implementation. Embedders define enum values from
   // VIEWS_INSETS_END. Values named beginning with "INSETS_" represent the
   // actual Insets: the rest are markers.
   VIEWS_INSETS_START = 0,
 
   // The margins around the contents area of a bubble (popover)-style dialog.
   INSETS_BUBBLE_CONTENTS = VIEWS_INSETS_START,
+  // The margins around the title of a bubble (popover)-style dialog.
+  INSETS_BUBBLE_TITLE,
   // The margins around the button row of a dialog.
   INSETS_DIALOG_BUTTON,
   // The margins around the icon/title of a dialog.
   INSETS_DIALOG_TITLE,
   // The margins that should be applied around a panel GridLayout.
   INSETS_PANEL,
   // Padding to add to vector image buttons to increase their click and touch
   // target size.
   INSETS_VECTOR_IMAGE_BUTTON,
 
@@ skipping 51 matching lines @@
 
  private:
   DefaultTypographyProvider typography_provider_;
 
   DISALLOW_COPY_AND_ASSIGN(LayoutProvider);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_LAYOUT_LAYOUT_PROVIDER_H_