Do not use win32k renderer lockdown if DirectWrite is disabled.

content/common/content_switches_internal.cc

 // Copyright (c) 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 "content/common/content_switches_internal.h"
 
 #include "base/command_line.h"
+#include "base/metrics/field_trial.h"
 #include "content/public/common/content_switches.h"
 
 #if defined(OS_WIN)
 #include "base/win/windows_version.h"
+#include "ui/gfx/win/direct_write.h"
 #endif
 
 namespace content {
 
 bool IsPinchToZoomEnabled() {
   const base::CommandLine& command_line =
       *base::CommandLine::ForCurrentProcess();
 
   // --disable-pinch should always disable pinch
   if (command_line.HasSwitch(switches::kDisablePinch))
     return false;
 
 #if defined(OS_WIN)
   return base::win::GetVersion() >= base::win::VERSION_WIN8;
 #elif defined(OS_CHROMEOS)
   return true;
 #else
   return command_line.HasSwitch(switches::kEnableViewport) ||
       command_line.HasSwitch(switches::kEnablePinch);
 #endif
 }
 
+#if defined(OS_WIN)
+
+bool IsWin32kRendererLockdownEnabled() {
+  const std::string group_name =
+      base::FieldTrialList::FindFullName("Win32kLockdown");
+  if (base::win::GetVersion() < base::win::VERSION_WIN8)
+    return false;
+  if (!gfx::win::ShouldUseDirectWrite())
+    return false;
+  const base::CommandLine* cmd_line = base::CommandLine::ForCurrentProcess();
+  if (cmd_line->HasSwitch(switches::kEnableWin32kRendererLockDown))
+    return true;
+  if (cmd_line->HasSwitch(switches::kDisableWin32kRendererLockDown))
+    return false;
+  // Default.
+  return group_name == "Enabled";
+}
+#endif
+
 } // namespace content