Make the edge where BackgroundGradientView draws a divider selectable.

chrome/browser/ui/cocoa/background_gradient_view.mm

Index: chrome/browser/ui/cocoa/background_gradient_view.mm
diff --git a/chrome/browser/ui/cocoa/background_gradient_view.mm b/chrome/browser/ui/cocoa/background_gradient_view.mm
index 6458533dbc51ed8db54c04fa93f229d46d37d96d..e0ee183f5c16c7243492e2f94fb0d6e4d95aabf5 100644
--- a/chrome/browser/ui/cocoa/background_gradient_view.mm
+++ b/chrome/browser/ui/cocoa/background_gradient_view.mm
@@ -12,31 +12,16 @@
 #import "ui/base/cocoa/nsview_additions.h"
 #include "ui/base/material_design/material_design_controller.h"
 
-@interface BackgroundGradientView (Private)
-- (void)commonInit;
-- (NSColor*)backgroundImageColor;
-@end
-
 @implementation BackgroundGradientView
 
+@synthesize divider = divider_;
 @synthesize showsDivider = showsDivider_;
 
-- (id)initWithFrame:(NSRect)frameRect {
-  if ((self = [super initWithFrame:frameRect])) {
-    [self commonInit];
-  }
-  return self;
-}
-
-- (id)initWithCoder:(NSCoder*)decoder {
-  if ((self = [super initWithCoder:decoder])) {
-    [self commonInit];
-  }
-  return self;
-}
-
-- (void)commonInit {
-  showsDivider_ = YES;

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

This used to default to divider-on, now it defaults to divider-off, no?

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

Fixed, thanks.

+- (void)setDivider:(BackgroundGradientViewDivider)divider {
+  if (divider_ == divider)
+    return;
+  divider_ = divider;
+  [self setNeedsDisplay:YES];
 }
 
 - (void)setShowsDivider:(BOOL)show {
@@ -68,10 +53,16 @@
   NSRectFillUsingOperation(dirtyRect, NSCompositeSourceOver);
 
   if (showsDivider_) {
-    // Draw bottom stroke
-    NSRect borderRect, contentRect;
-    NSDivideRect([self bounds], &borderRect, &contentRect, [self cr_lineWidth],
-                 NSMinYEdge);
+    CGFloat lineWidth = [self cr_lineWidth];
+    NSRect borderRect = NSMakeRect(0, 0, self.bounds.size.width, lineWidth);
+
+    switch (divider_) {
+      case BackgroundGradientViewDivider::Bottom:
+        break;
+      case BackgroundGradientViewDivider::Top:
+        borderRect.origin.y = self.bounds.size.height - lineWidth;
+        break;
+    }

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

These 7 lines are shorter as

  if (divider_ == BackgroundGradientViewDivider::Top)
    borderRect.origin.y = NSHeight(self.bounds) - lineWidth;

But I'd probably leave the previous code and tweak it like so:

  NSDivideRect([self bounds], &borderRect, &contentRect, [self cr_lineWidth],
    divider_ == BackgroundGradientViewDivider::Top ? NSMaxYEdge : NSMinYEdge);

And if you don't make up your own enum but use NSMaxYEdge / NSMinYEdge instead,
then you don't even need the ternary.

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

I think I had an incomplete understanding of NSDivideRect. I like this idea much
better.

     if (NSIntersectsRect(borderRect, dirtyRect)) {
       [[self strokeColor] set];
       NSRectFillUsingOperation(NSIntersectionRect(borderRect, dirtyRect),