[content shell] When running layout tests on mac, move the window off-screen

content/shell/shell_mac.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.
 
 #include "content/shell/shell.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #import "base/memory/scoped_nsobject.h"
@@ skipping 146 matching lines @@
 }
 
 void Shell::PlatformCreateWindow(int width, int height) {
   NSRect initial_window_bounds =
       NSMakeRect(0, 0, width, height + kURLBarHeight);
   NSRect content_rect = initial_window_bounds;
   NSUInteger style_mask = NSTitledWindowMask |
                           NSClosableWindowMask |
                           NSMiniaturizableWindowMask |
                           NSResizableWindowMask;
+  if (headless_) {
+    content_rect = NSOffsetRect(initial_window_bounds, -10000, -10000);
+    style_mask = NSBorderlessWindowMask;
+  }
   CrShellWindow* window =
       [[CrShellWindow alloc] initWithContentRect:content_rect
                                        styleMask:style_mask
                                          backing:NSBackingStoreBuffered
                                            defer:NO];
   window_ = window;
   [window setShell:this];
   [window_ setTitle:kWindowTitle];
   NSView* content = [window_ contentView];
 
@@ skipping 113 matching lines @@
         [[event.os_event characters] isEqual:@"l"]) {
       [window_ makeFirstResponder:url_edit_view_];
       return;
     }
 
     [[NSApp mainMenu] performKeyEquivalent:event.os_event];
   }
 }
 
 }  // namespace content