MacViews: Fix window dragging on Sierra.

ui/views/cocoa/views_nswindow_delegate.h

 // Copyright 2014 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 UI_VIEWS_COCOA_VIEWS_NSWINDOW_DELEGATE_H_
 #define UI_VIEWS_COCOA_VIEWS_NSWINDOW_DELEGATE_H_
 
 #import <Cocoa/Cocoa.h>
 
 #import "base/mac/scoped_nsobject.h"
@@ skipping 37 matching lines @@
 // Called on the delegate of a modal sheet when its modal session ends.
 - (void)sheetDidEnd:(NSWindow*)sheet
          returnCode:(NSInteger)returnCode
         contextInfo:(void*)contextInfo;
 
 // Redeclare methods defined in the protocol NSWindowDelegate which are only
 // available on OSX 10.7+.
 - (void)windowDidFailToEnterFullScreen:(NSWindow*)window;
 - (void)windowDidFailToExitFullScreen:(NSWindow*)window;
 
-// Called when the application receives a mouse-down, but before the event
-// is processed by NSWindows. Returns NO if the event should be processed as-is,
-// or YES if the event should be reposted to handle window dragging. Events are
-// reposted at the CGSessionEventTap level because window dragging happens there
-// before the application receives the event.
-- (BOOL)shouldRepostPendingLeftMouseDown:(NSPoint)locationInWindow;
-
 @end
 
 #endif  // UI_VIEWS_COCOA_VIEWS_NSWINDOW_DELEGATE_H_