Make the edge where BackgroundGradientView draws a divider selectable.

chrome/browser/ui/cocoa/background_gradient_view.mm

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/ui/cocoa/background_gradient_view.h"
 
 #import "chrome/browser/themes/theme_properties.h"
 #import "chrome/browser/themes/theme_service.h"
 #import "chrome/browser/ui/cocoa/themed_window.h"
 #include "chrome/grit/theme_resources.h"
 #import "ui/base/cocoa/nsgraphics_context_additions.h"
 #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 showsDivider = showsDivider_;
+@synthesize dividerEdge = dividerEdge_;
 
 - (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;
+  dividerEdge_ = NSMinYEdge;
 }
 
 - (void)setShowsDivider:(BOOL)show {
   if (showsDivider_ == show)
     return;
   showsDivider_ = show;
   [self setNeedsDisplay:YES];
 }
 
+- (void)setDividerEdge:(NSRectEdge)dividerEdge {
+  if (dividerEdge_ == dividerEdge)
+    return;
+  dividerEdge_ = dividerEdge;
+  [self setNeedsDisplay:YES];
+}
+
 - (NSPoint)patternPhase {
   return [[self window]
       themeImagePositionForAlignment:THEME_IMAGE_ALIGN_WITH_TAB_STRIP];
 }
 
 - (void)drawRect:(NSRect)dirtyRect {
   [[NSGraphicsContext currentContext]
       cr_setPatternPhase:[self patternPhase]
                  forView:[self cr_viewBeingDrawnTo]];
 
   const ui::ThemeProvider* themeProvider = [[self window] themeProvider];
   if (themeProvider && !themeProvider->UsingSystemTheme()) {
     // If the background image is semi transparent then we need something
     // to blend against. Using 20% black gives us a color similar to Windows.
     [[NSColor colorWithCalibratedWhite:0.2 alpha:1.0] set];
     NSRectFill(dirtyRect);
   }
 
   [[self backgroundImageColor] set];
   NSRectFillUsingOperation(dirtyRect, NSCompositeSourceOver);
 
   if (showsDivider_) {
-    // Draw bottom stroke
+    // Draw stroke
     NSRect borderRect, contentRect;
     NSDivideRect([self bounds], &borderRect, &contentRect, [self cr_lineWidth],
-                 NSMinYEdge);
+                 dividerEdge_);
     if (NSIntersectsRect(borderRect, dirtyRect)) {
       [[self strokeColor] set];
       NSRectFillUsingOperation(NSIntersectionRect(borderRect, dirtyRect),
                                NSCompositeSourceOver);
     }
   }
 }
 
 - (NSColor*)strokeColor {
   NSWindow* window = [self window];
@@ skipping 90 matching lines @@
 
 - (void)windowDidChangeTheme {
   [self setNeedsDisplay:YES];
 }
 
 - (void)windowDidChangeActive {
   [self setNeedsDisplay:YES];
 }
 
 @end