Add support for observing tracking areas so that when tabs are moved undernea...

chrome/browser/cocoa/tab_view.mm

 // Copyright (c) 2009 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/cocoa/tab_view.h"
 
 #include "base/logging.h"
 #include "base/nsimage_cache_mac.h"
 #import "chrome/browser/cocoa/tab_controller.h"
 #import "chrome/browser/cocoa/tab_window_controller.h"
@@ skipping 98 matching lines @@
   if ([theEvent trackingArea] == closeTrackingArea_) {
     [closeButton_ setImage:nsimage_cache::ImageNamed(@"close_bar.pdf")];
   } else {
     lastHoverUpdate_ = [NSDate timeIntervalSinceReferenceDate];
     isMouseInside_ = NO;
     [self adjustHoverValue];
     [self setNeedsDisplay:YES];
   }
 }
 
+// The tracking areas have been moved. Make sure that the close button is
+// highlighting correctly with respect to the cursor position with the new
+// tracking area locations.
+- (void)updateTrackingAreas {
+  [super updateTrackingAreas];
+
+  // Update the close buttons if the tab has moved.
+  NSPoint mouseLoc = [[self window] mouseLocationOutsideOfEventStream];
+  mouseLoc = [self convertPointFromBase:mouseLoc];
+  NSString* name = nil;
+  if (NSPointInRect(mouseLoc, [closeButton_ frame])) {
+    name = @"close_bar_h.pdf";
+  } else {
+    name = @"close_bar.pdf";
+  }
+  NSImage* newImage = nsimage_cache::ImageNamed(name);
+  NSImage* buttonImage = [closeButton_ image];
+  if (![buttonImage isEqual:newImage]) {
+    [closeButton_ setImage:newImage];
+  }
+}
+
 // 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]];
   NSRect frame = [self frame];
 
   // Reduce the width of the hit rect slightly to remove the overlap
   // between adjacent tabs.  The drawing code in TabCell has the top
   // corners of the tab inset by height*2/3, so we inset by half of
   // that here.  This doesn't completely eliminate the overlap, but it
@@ skipping 640 matching lines @@
 }
 
 - (void)viewDidMoveToWindow {
   [super viewDidMoveToWindow];
   if ([self window]) {
     [controller_ updateTitleColor];
   }
 }
 
 @end