Delete IsAtLeastOS10_9() and IsAtMostOS10_9()

chrome/browser/ui/cocoa/browser_window_controller_private.mm

 // 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.
 
 #import "chrome/browser/ui/cocoa/browser_window_controller_private.h"
 
 #include <cmath>
 
 #import "base/auto_reset.h"
 #include "base/command_line.h"
@@ skipping 1098 matching lines @@
   // Add in the subviews above the tabContentArea.
   for (NSUInteger i = index + 1; i < [subviews count]; ++i) {
     NSView* view = [subviews objectAtIndex:i];
     [self.chromeContentView addSubview:view
                             positioned:NSWindowAbove
                             relativeTo:nil];
   }
 }
 
 + (BOOL)systemSettingsRequireMavericksAppKitFullscreenHack {
-  if (!base::mac::IsOS10_9())
+  if (base::mac::IsAtLeastOS10_10())
     return NO;
   return [NSScreen respondsToSelector:@selector(screensHaveSeparateSpaces)] &&
          [NSScreen screensHaveSeparateSpaces];
 }
 
 - (BOOL)shouldUseMavericksAppKitFullscreenHack {
   if (![[self class] systemSettingsRequireMavericksAppKitFullscreenHack])
     return NO;
   if (!enteringAppKitFullscreen_)
     return NO;
@@ skipping 138 matching lines @@
   if (fullscreenLowPowerCoordinator_)
     fullscreenLowPowerCoordinator_->SetHasActiveSheet(false);
 }
 
 - (void)childWindowsDidChange {
   if (fullscreenLowPowerCoordinator_)
     fullscreenLowPowerCoordinator_->ChildWindowsChanged();
 }
 
 @end  // @implementation BrowserWindowController(Private)