[Mac] Properly show and hide the avatar button for the one-profile case.

chrome/browser/ui/cocoa/browser/avatar_button_controller.h

Index: chrome/browser/ui/cocoa/browser/avatar_button_controller.h
diff --git a/chrome/browser/ui/cocoa/browser/avatar_button_controller.h b/chrome/browser/ui/cocoa/browser/avatar_button_controller.h
new file mode 100644
index 0000000000000000000000000000000000000000..e0d35de1cc9875a09f3c7185a57a51a21eac1071
--- /dev/null
+++ b/chrome/browser/ui/cocoa/browser/avatar_button_controller.h
@@ -0,0 +1,44 @@
+// Copyright (c) 2011 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.
+
+#ifndef CHROME_BROWSER_UI_COCOA_BROWSER_AVATAR_BUTTON_CONTROLLER_H_
+#define CHROME_BROWSER_UI_COCOA_BROWSER_AVATAR_BUTTON_CONTROLLER_H_
+#pragma once
+
+#import <AppKit/AppKit.h>
+
+#include "base/memory/scoped_nsobject.h"
+#include "base/memory/scoped_ptr.h"
+
+class Browser;
+
+namespace AvatarButtonControllerInternal {
+class Observer;
+}
+
+// This view controller manages the button/image that sits in the top of the
+// window frame when using multi-profiles. It shows the current profile's
+// avatar, or, when in Incognito, the spy dude. With multi-profiles, clicking
+// will open the profile menu; in Incognito, clicking will do nothing.
+@interface AvatarButtonController : NSViewController {
+ @private
+  Browser* browser_;
+
+  // Notification bridge for profile info updates.
+  scoped_ptr<AvatarButtonControllerInternal::Observer> observer_;
+}
+
+// The view cast to a button.
+@property (readonly, nonatomic) NSButton* buttonView;
+
+// Designated initializer.
+- (id)initWithBrowser:(Browser*)browser;
+
+// Sets the image to be used as the avatar. This will have a drop shadow applied
+// and will be resized to the frame of the button.
+- (void)setImage:(NSImage*)image;
+
+@end
+
+#endif  // CHROME_BROWSER_UI_COCOA_BROWSER_AVATAR_BUTTON_CONTROLLER_H_