Make the edge where BackgroundGradientView draws a divider selectable.

chrome/browser/ui/cocoa/background_gradient_view.h

 // Copyright (c) 2011 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_COCOA_BACKGROUND_GRADIENT_VIEW_H_
 #define CHROME_BROWSER_UI_COCOA_BACKGROUND_GRADIENT_VIEW_H_
 
 #import <Cocoa/Cocoa.h>
 
 #import "chrome/browser/ui/cocoa/themed_window.h"
 
+enum class BackgroundGradientViewDivider {

[Nico, 2016/09/12 13:45:55]

why enum class? can we come up with something shorter than
`BackgroundGradientViewDivider::Bottom` too?

[Sidney San Martín, 2016/09/14 17:46:59]

I'd rather shove one name into the global namespace than two (re. using an enum
class), and naming it after the class seemed consistent with Apple style. What
would you've done?

+  Bottom,
+  Top,
+};
+
 // A custom view that draws a 'standard' background gradient.
 // Base class for other Chromium views.
-@interface BackgroundGradientView : NSView<ThemedWindowDrawing> {
- @private
-  BOOL showsDivider_;
-}
+@interface BackgroundGradientView : NSView<ThemedWindowDrawing>
 
-// Controls whether the bar draws a dividing line at the bottom.
+// Controls where and if the bar draws a dividing line.
+@property(nonatomic, assign) BackgroundGradientViewDivider divider;
 @property(nonatomic, assign) BOOL showsDivider;
 
 // The color used for the bottom stroke. Public so subclasses can use.
 - (NSColor*)strokeColor;
 
 // The pattern phase that will be used by -drawRect:.
 // Defaults to align the top of the theme image with the top of the tabs.
 // Views that draw at the bottom of the window (download bar) can override to
 // change the pattern phase.
 - (NSPoint)patternPhase;
 
 @end
 
 #endif  // CHROME_BROWSER_UI_COCOA_BACKGROUND_GRADIENT_VIEW_H_