Mac: Use [NSArray firstObject] for [NSScreen screens]

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>
 
 #include "base/command_line.h"
 #include "base/mac/bind_objc_block.h"
@@ skipping 104 matching lines @@
 - (void)saveWindowPositionIfNeeded {
   if (!chrome::ShouldSaveWindowPlacement(browser_.get()))
     return;
 
   // If we're in fullscreen mode, save the position of the regular window
   // instead.
   NSWindow* window =
       [self isInAnyFullscreenMode] ? savedRegularWindow_ : [self window];
 
   // Window positions are stored relative to the origin of the primary monitor.
-  NSRect monitorFrame = [[[NSScreen screens] objectAtIndex:0] frame];
+  NSRect monitorFrame = [[[NSScreen screens] firstObject] frame];
   NSScreen* windowScreen = [window screen];
 
   // Start with the window's frame, which is in virtual coordinates.
   // Do some y twiddling to flip the coordinate system.
   gfx::Rect bounds(NSRectToCGRect([window frame]));
   bounds.set_y(monitorFrame.size.height - bounds.y() - bounds.height());
 
   // Browser::SaveWindowPlacement saves information for session restore.
   ui::WindowShowState show_state = ui::SHOW_STATE_NORMAL;
   if ([window isMiniaturized])
@@ skipping 539 matching lines @@
                                                   : CANONICAL_FULLSCREEN);
 
   if (notification)  // For System Fullscreen when non-nil.
     [self registerForContentViewResizeNotifications];
 
   NSWindow* window = [self window];
   savedRegularWindowFrame_ = [window frame];
 
   enteringAppKitFullscreen_ = YES;
   enteringAppKitFullscreenOnPrimaryScreen_ =
-      [[[self window] screen] isEqual:[[NSScreen screens] objectAtIndex:0]];
+      [[[self window] screen] isEqual:[[NSScreen screens] firstObject]];
 
   fullscreen_mac::SlidingStyle style;
   if (browser_->exclusive_access_manager()
           ->fullscreen_controller()
           ->IsWindowFullscreenForTabOrPending()) {
     style = fullscreen_mac::OMNIBOX_TABS_NONE;
   } else if (enteringPresentationMode_) {
     style = fullscreen_mac::OMNIBOX_TABS_HIDDEN;
   } else {
     style = fullscreen_mac::OMNIBOX_TABS_PRESENT;
@@ skipping 395 matching lines @@
 
   NSView* root = [[self.window contentView] superview];
   if (!root.layer)
     return NO;
 
   // AppKit on OSX 10.9 has a bug for applications linked against OSX 10.8 SDK
   // and earlier. Under specific circumstances, it prevents the custom AppKit
   // transition from working well. See http://crbug.com/396980 for more
   // details.
   if ([[self class] systemSettingsRequireMavericksAppKitFullscreenHack] &&
-      ![[[self window] screen] isEqual:[[NSScreen screens] objectAtIndex:0]]) {
+      ![[[self window] screen] isEqual:[[NSScreen screens] firstObject]]) {
     return NO;
   }
 
   return YES;
 }
 
 - (NSArray*)customWindowsToEnterFullScreenForWindow:(NSWindow*)window {
   DCHECK([window isEqual:self.window]);
 
   if (![self shouldUseCustomAppKitFullscreenTransition:YES])
@@ skipping 45 matching lines @@
   return browser_->tab_strip_model()->GetActiveWebContents();
 }
 
 - (PermissionBubbleManager*)permissionBubbleManager {
   if (WebContents* contents = [self webContents])
     return PermissionBubbleManager::FromWebContents(contents);
   return nil;
 }
 
 @end  // @implementation BrowserWindowController(Private)