Implemented fullscreen exit animation with AppKit

chrome/browser/ui/cocoa/browser_window_controller.mm

Index: chrome/browser/ui/cocoa/browser_window_controller.mm
diff --git a/chrome/browser/ui/cocoa/browser_window_controller.mm b/chrome/browser/ui/cocoa/browser_window_controller.mm
index 4be4668efd342e41070120ca9a5e8290959681db..0abcb706be9a73918ba8fbdd81867c151f1d095e 100644
--- a/chrome/browser/ui/cocoa/browser_window_controller.mm
+++ b/chrome/browser/ui/cocoa/browser_window_controller.mm
@@ -1950,6 +1950,7 @@ using content::WebContents;
   // and |layoutSubviews| computes the FindBar's position.
   // TODO: calling |layoutSubviews| here is a waste, find a better way to
   // do this.
+
   if ([findBarCocoaController_ isFindBarVisible])
     [self layoutSubviews];
 }
@@ -2151,9 +2152,10 @@ willAnimateFromState:(BookmarkBar::State)oldState
 }
 
 - (BOOL)isInAppKitFullscreen {
-  return ([[self window] styleMask] & NSFullScreenWindowMask) ==
+  return !exitingAppKitFullscreen_ &&
+          (([[self window] styleMask] & NSFullScreenWindowMask) ==
              NSFullScreenWindowMask ||
-         enteringAppKitFullscreen_;
+               enteringAppKitFullscreen_);
 }
 
 - (void)enterExtensionFullscreenForURL:(const GURL&)url