Delete IsAtLeastOS10_9() and IsAtMostOS10_9()

ui/views/cocoa/bridged_native_widget.mm

 // 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.
 
 #import "ui/views/cocoa/bridged_native_widget.h"
 
 #import <objc/runtime.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 764 matching lines @@
     UpdateLayerProperties();
     if ([window_ inLiveResize])
       MaybeWaitForFrame(new_size);
   }
 
   // 10.9 is unable to generate a window shadow from the composited CALayer, so
   // use Quartz.
   // We don't update the window mask during a live resize, instead it is done
   // after the resize is completed in viewDidEndLiveResize: in
   // BridgedContentView.
-  if (base::mac::IsOS10_9() && ![window_ inLiveResize])
+  if (!base::mac::IsAtLeastOS10_10() && ![window_ inLiveResize])
     [bridged_view_ updateWindowMask];
 }
 
 void BridgedNativeWidget::OnPositionChanged() {
   native_widget_mac_->GetWidget()->OnNativeWidgetMove();
 }
 
 void BridgedNativeWidget::OnVisibilityChanged() {
   const bool window_visible = [window_ isVisible];
   if (window_visible_ == window_visible)
@@ skipping 569 matching lines @@
   [bridged_view_ setMouseDownCanMoveWindow:draggable];
   // AppKit will not update its cache of mouseDownCanMoveWindow unless something
   // changes. Previously we tried adding an NSView and removing it, but for some
   // reason it required reposting the mouse-down event, and didn't always work.
   // Calling the below seems to be an effective solution.
   [window_ setMovableByWindowBackground:NO];
   [window_ setMovableByWindowBackground:YES];
 }
 
 }  // namespace views