[Mac] Fix Toolbar glimpse during fullscreen transition

chrome/browser/ui/cocoa/browser_window_controller.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_COCOA_BROWSER_WINDOW_CONTROLLER_H_
 #define CHROME_BROWSER_UI_COCOA_BROWSER_WINDOW_CONTROLLER_H_
 
 // A class acting as the Objective-C controller for the Browser
 // object. Handles interactions between Cocoa and the cross-platform
 // code. Each window has a single toolbar and, by virtue of being a
@@ skipping 423 matching lines @@
 
 // Called to check if this controller's window is a tabbed window (e.g., not a
 // pop-up window). Returns YES if it is, NO otherwise.
 // Note: The |-has...| methods are usually preferred, so this method is largely
 // deprecated.
 - (BOOL)isTabbedWindow;
 
 // Returns the size of the original (non-fullscreen) window.
 - (NSRect)savedRegularWindowFrame;
 
+// Returns true if the browser is in the process of entering/exiting
+// fullscreen.
+- (BOOL)isFullscreenTransitionInProgress;
+
 @end  // @interface BrowserWindowController(WindowType)
 
 // Fullscreen terminology:
 //
 // ----------------------------------------------------------------------------
 // There are 2 APIs that cause the window to get resized, and possibly move
 // spaces.
 //
 // + AppKitFullscreen API: AppKit touts a feature known as "fullscreen". This
 // involves moving the current window to a different space, and resizing the
@@ skipping 206 matching lines @@
 // Returns the active tab contents controller's |blockFullscreenResize_| flag.
 - (BOOL)isActiveTabContentsControllerResizeBlocked;
 
 // Returns the presentation mode controller.
 - (PresentationModeController*)presentationModeController;
 
 @end  // @interface BrowserWindowController (TestingAPI)
 
 
 #endif  // CHROME_BROWSER_UI_COCOA_BROWSER_WINDOW_CONTROLLER_H_