[Mac] Adds a flag to force 10.6-style fullscreen for testing.

chrome/browser/fullscreen_mac.mm

 // Copyright (c) 2011 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/fullscreen.h"
 
 #import <Cocoa/Cocoa.h>
 
+#include "base/command_line.h"
+#include "base/mac/mac_util.h"
+#include "chrome/common/chrome_switches.h"
+
 // Replicate specific 10.7 SDK declarations for building with prior SDKs.
 #if !defined(MAC_OS_X_VERSION_10_7) || \
     MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
 
 enum {
   NSApplicationPresentationFullScreen = 1 << 10
 };
 
 #endif  // MAC_OS_X_VERSION_10_7
 
@@ skipping 14 matching lines @@
   // If both dock and menu bar are hidden, that is the equivalent of the Carbon
   // SystemUIMode (or Info.plist's LSUIPresentationMode) kUIModeAllHidden.
   if (dock_hidden && menu_hidden)
     return true;
 
   if (options & NSApplicationPresentationFullScreen)
     return true;
 
   return false;
 }
+
+namespace chrome {
+namespace mac {
+
+bool SupportsSystemFullscreen() {
+  const CommandLine* command_line = CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kDisableSystemFullscreenForTesting))
+    return false;
+
+  return base::mac::IsOSLionOrLater();
+}
+
+}  // namespace mac
+}  // namespace chrome