[Mac] Use Core Graphics to draw the close button used within tabs, infobars, ...

chrome/browser/cocoa/hover_close_button.h

-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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 <Cocoa/Cocoa.h>
 
 #include "base/scoped_nsobject.h"
 
-// The standard close button for our Mac UI which is the "x"
-// that changes to the red circle with the "x" when you hover over it.
-// At this time it is used by the popup blocker, download bar, info bar
-// and tabs.
+// The standard close button for our Mac UI which is the "x" that changes to a
+// dark circle with the "x" when you hover over it. At this time it is used by
+// the popup blocker, download bar, info bar and tabs.
 @interface HoverCloseButton : NSButton {
-  // Tracking area for close button mouseover images.
+ @private
+  // Enumeration of the hover states that the close button can be in at any one
+  // time. The button cannot be in more than one hover state at a time.
+  enum HoverState {
+    kHoverStateNone = 0,
+    kHoverStateMouseOver = 1,
+    kHoverStateMouseDown = 2
+  };
+
+  HoverState hoverState_;
+
+  // Tracking area for close button mouseover states.
   scoped_nsobject<NSTrackingArea> closeTrackingArea_;
+
+  // Bezier path for drawing the 'x' within the button.
+  scoped_nsobject<NSBezierPath> xPath_;
+
+  // Bezier path for drawing the hover state circle behind the 'x'.
+  scoped_nsobject<NSBezierPath> circlePath_;
 }
 
 // Enables or disables the |NSTrackingRect|s for the button.
 - (void)setTrackingEnabled:(BOOL)enabled;
 
-// Sets up the button's images, tracking areas, and accessibility info
-// when instantiated via initWithFrame or awakeFromNib.
+// Sets up the button's tracking areas and accessibility info when instantiated
+// via initWithFrame or awakeFromNib.
 - (void)commonInit;
 
 // Checks to see whether the mouse is in the button's bounds and update
 // the image in case it gets out of sync.  This occurs when you close a
 // tab so the tab to the left of it takes its place, and drag the button
 // without moving the mouse before you press the button down.
 - (void)checkImageState;
 
 @end