[Mac] Refactor the fullscreen menubar

chrome/browser/ui/cocoa/fullscreen/fullscreen_menubar_tracker.h

+// Copyright 2016 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_FULLSCREEN_FULLSCREEN_MENUBAR_TRACKER_H_
+#define CHROME_BROWSER_UI_COCOA_FULLSCREEN_FULLSCREEN_MENUBAR_TRACKER_H_
+
+#import <Cocoa/Cocoa.h>
+
+@class BrowserWindowController;
+@class FullscreenToolbarController;
+
+// State of the menubar in the window's screen.
+enum class FullscreenMenubarState {
+  SHOWN,    // Menubar is fully shown.
+  HIDDEN,   // Menubar is fully hidden.
+  SHOWING,  // Menubar is animating in.
+  HIDING,   // Menubar is animating out.
+};
+
+@interface FullscreenMenubarTracker : NSObject
+
+// The state of the menubar.
+@property(nonatomic, readonly) FullscreenMenubarState state;
+
+// The fraction of the menubar shown on the screen.
+@property(nonatomic, readonly) CGFloat menubarFraction;
+
+// Designated initializer.
+- (instancetype)initWithFullscreenToolbarController:
+    (FullscreenToolbarController*)owner;
+
+// Called by MenuBarRevealHandler to update the menubar progress. The progress
+// is only updated if the window is in fullscreen and the mouse is in the
+// same screen.
+- (void)setMenubarProgress:(CGFloat)progress;
+
+@end
+
+#endif  // CHROME_BROWSER_UI_COCOA_FULLSCREEN_FULLSCREEN_MENUBAR_TRACKER_H_