Restrict PPAPI Win32k lockdown to Win10 and above.

chrome/browser/chrome_content_browser_client.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 "chrome/browser/chrome_content_browser_client.h"
 
 #include <map>
 #include <set>
 #include <utility>
 #include <vector>
@@ skipping 2677 matching lines @@
       sandbox::TargetPolicy::SUBSYS_NAMED_PIPES,
       sandbox::TargetPolicy::NAMEDPIPES_ALLOW_ANY,
       L"\\\\.\\pipe\\chrome.nacl.*");
   if (result != sandbox::SBOX_ALL_OK)
     return false;
   return result == sandbox::SBOX_ALL_OK;
 }
 
 bool ChromeContentBrowserClient::IsWin32kLockdownEnabledForMimeType(
     const std::string& mime_type) const {
+  // We don't support PPAPI win32k lockdown prior to Windows 10.
+  if (base::win::GetVersion() < base::win::VERSION_WIN10)
+    return false;
   // First, check if any variation parameters have enabled or disabled this
   // mime type either specifically or globally.
   std::map<std::string, std::string> mime_params;
   if (variations::GetVariationParams("EnableWin32kLockDownMimeTypes",
                                      &mime_params)) {
     bool enabled = false;
     for (const auto& param : mime_params) {
       if (param.first == mime_type || param.first == "*") {
         // Disabled entries take precedence over Enabled entries.
         if (base::StartsWith(param.second, "Disabled",
@@ skipping 276 matching lines @@
   if (channel <= kMaxDisableEncryptionChannel) {
     static const char* const kWebRtcDevSwitchNames[] = {
       switches::kDisableWebRtcEncryption,
     };
     to_command_line->CopySwitchesFrom(from_command_line,
                                       kWebRtcDevSwitchNames,
                                       arraysize(kWebRtcDevSwitchNames));
   }
 }
 #endif  // defined(ENABLE_WEBRTC)