[Mac] User manager should open on the screen that has focus

chrome/browser/ui/cocoa/profiles/user_manager_mac.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.
 
 #include "chrome/browser/ui/cocoa/profiles/user_manager_mac.h"
 
 #include "chrome/app/chrome_command_ids.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/browser_dialogs.h"
@@ skipping 74 matching lines @@
 - (void)show;
 - (void)close;
 - (BOOL)isVisible;
 @end
 
 @implementation UserManagerWindowController
 
 - (id)initWithProfile:(Profile*)profile
          withObserver:(UserManagerMac*)userManagerObserver {
 
-  // Center the window on the primary screen.
-  CGFloat screenHeight =
-      [[[NSScreen screens] objectAtIndex:0] frame].size.height;
-  CGFloat screenWidth =
-      [[[NSScreen screens] objectAtIndex:0] frame].size.width;
+  // Center the window on the screen that currently has focus.
+  NSScreen* mainScreen = [NSScreen mainScreen];
+  CGFloat screenHeight = [mainScreen frame].size.height;
+  CGFloat screenWidth = [mainScreen frame].size.width;
 
   NSRect contentRect = NSMakeRect((screenWidth - kWindowWidth) / 2,
                                   (screenHeight - kWindowHeight) / 2,
                                   kWindowWidth, kWindowHeight);
   ChromeEventProcessingWindow* window = [[ChromeEventProcessingWindow alloc]
       initWithContentRect:contentRect
                 styleMask:NSTitledWindowMask |
                           NSClosableWindowMask |
                           NSResizableWindowMask
                   backing:NSBackingStoreBuffered
-                    defer:NO];
+                    defer:NO
+                   screen:mainScreen];
   [window setTitle:l10n_util::GetNSString(IDS_PRODUCT_NAME)];
   [window setMinSize:NSMakeSize(kWindowWidth, kWindowHeight)];
 
   if ((self = [super initWithWindow:window])) {
     userManagerObserver_ = userManagerObserver;
 
     // Initialize the web view.
     webContents_.reset(content::WebContents::Create(
         content::WebContents::CreateParams(profile)));
     window.contentView = webContents_->GetNativeView();
@@ skipping 85 matching lines @@
 void UserManagerMac::OnGuestProfileCreated(Profile* guest_profile,
                                            const std::string& url) {
   instance_ = new UserManagerMac(guest_profile);
   [instance_->window_controller_ showURL:GURL(url)];
 }
 
 void UserManagerMac::WindowWasClosed() {
   instance_ = NULL;
   delete this;
 }