Win32k lockdown: move to chrome://flags, add UMA, add finch

content/public/common/content_switches.cc

 // 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/public/common/content_switches.h"
 
 #include "base/command_line.h"
+#include "base/metrics/field_trial.h"
 
 namespace switches {
 
 // The number of MSAA samples for canvas2D. Requires MSAA support by GPU to
 // have an effect. 0 disables MSAA.
 const char kAcceleratedCanvas2dMSAASampleCount[] = "canvas-msaa-sample-count";
 
 // By default, file:// URIs cannot read other file:// URIs. This is an
 // override for developers who need the old behavior for testing.
 const char kAllowFileAccessFromFiles[]      = "allow-file-access-from-files";
@@ skipping 956 matching lines @@
     "enable-threaded-event-handling-mac";
 #endif
 
 #if defined(OS_WIN)
 // Device scale factor passed to certain processes like renderers, etc.
 const char kDeviceScaleFactor[]     = "device-scale-factor";
 
 // Disable the Legacy Window which corresponds to the size of the WebContents.
 const char kDisableLegacyIntermediateWindow[] = "disable-legacy-window";
 
-// Enable the Win32K process mitigation policy for renderer processes which
-// prevents them from invoking user32 and gdi32 system calls which enter
-// the kernel. This is only supported on Windows 8 and beyond.
-const char kEnableWin32kRendererLockDown[]
-    = "enable_win32k_renderer_lockdown";
+// Enables or disables the Win32K process mitigation policy for renderer
+// processes which prevents them from invoking user32 and gdi32 system calls
+// which enter the kernel. This is only supported on Windows 8 and beyond.
+const char kEnableWin32kRendererLockDown[] =
+    "enable-win32k-renderer-lockdown";
+const char kDisableWin32kRendererLockDown[] =
+    "disable-win32k-renderer-lockdown";
 
 // DirectWrite FontCache is shared by browser to renderers using shared memory.
 // This switch allows specifying suffix to shared memory section name to avoid
 // clashes between different instances of Chrome.
 const char kFontCacheSharedMemSuffix[] = "font-cache-shared-mem-suffix";
 #endif
 
 #if defined(ENABLE_PLUGINS)
 // Enables the plugin power saver feature.
 const char kEnablePluginPowerSaver[] = "enable-plugin-power-saver";
 #endif
 
+#if defined(OS_WIN)
+bool Win32kRendererLockdownEnabled() {
+  const std::string group_name =
+      base::FieldTrialList::FindFullName("Win32kLockdown");
+  if (CommandLine::ForCurrentProcess()->HasSwitch(

[Alexei Svitkine (slow), 2014/12/10 22:42:28]

Nit: Maybe put CommandLine::ForCurrentProcess() in a local var to make these not
wrap.

[Will Harris, 2014/12/11 18:35:58]

Done.

+          kEnableWin32kRendererLockDown))
+    return true;
+
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          kDisableWin32kRendererLockDown))
+    return false;
+
+  // Default.
+  return group_name == "Enabled";
+}
+#endif
+
 // Don't dump stuff here, follow the same order as the header.
 
 }  // namespace switches