mac: Pixel-based click detection for the tab close button

chrome/browser/ui/cocoa/tabs/tab_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.
 
 #import "chrome/browser/ui/cocoa/tabs/tab_view.h"
 
 #include "base/logging.h"
 #include "chrome/browser/themes/theme_service.h"
 #import "chrome/browser/ui/cocoa/nsview_additions.h"
 #import "chrome/browser/ui/cocoa/tabs/tab_controller.h"
@@ skipping 129 matching lines @@
 - (void)setTrackingEnabled:(BOOL)enabled {
   if (![closeButton_ isHidden]) {
     [closeButton_ setTrackingEnabled:enabled];
   }
 }
 
 // Determines which view a click in our frame actually hit. It's either this
 // view or our child close button.
 - (NSView*)hitTest:(NSPoint)aPoint {
   NSPoint viewPoint = [self convertPoint:aPoint fromView:[self superview]];
-  if (![closeButton_ isHidden])
-    if (NSPointInRect(viewPoint, [closeButton_ frame])) return closeButton_;
+  if (![closeButton_ isHidden]) {
+    if (NSPointInRect(viewPoint,[closeButton_ frame]) &&
+        [closeButton_ hitTest:viewPoint]) {
+      return closeButton_;
+    }
+  }
 
   NSRect pointRect = NSMakeRect(viewPoint.x, viewPoint.y, 1, 1);
 
   ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
   NSImage* left = rb.GetNativeImageNamed(IDR_TAB_ALPHA_LEFT).ToNSImage();
   if (viewPoint.x < [left size].width) {
     NSRect imageRect = NSMakeRect(0, 0, [left size].width, [left size].height);
     if ([left hitTestRect:pointRect withImageDestinationRect:imageRect
           context:nil hints:nil flipped:NO]) {
       return self;
@@ skipping 534 matching lines @@
   CGFloat middleWidth = tabWidth - leftWidth - rightWidth;
   NSRect middleRect = NSMakeRect(leftWidth, 0, middleWidth, kFillHeight);
   [[NSColor whiteColor] setFill];
   NSRectFill(middleRect);
 
   maskCache_.reset(CGBitmapContextCreateImage(maskContext));
   return maskCache_;
 }
 
 @end  // @implementation TabView(Private)