Make the edge where BackgroundGradientView draws a divider selectable.

chrome/browser/ui/cocoa/background_gradient_view.h

Index: chrome/browser/ui/cocoa/background_gradient_view.h
diff --git a/chrome/browser/ui/cocoa/background_gradient_view.h b/chrome/browser/ui/cocoa/background_gradient_view.h
index 433fe1f590f7e9ce55516c2e984c8f8b2f084512..ae6f4de816a6b6dcf50255d6c30cfefba8a2d936 100644
--- a/chrome/browser/ui/cocoa/background_gradient_view.h
+++ b/chrome/browser/ui/cocoa/background_gradient_view.h
@@ -9,14 +9,17 @@
 
 #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.