Add command line option to enable PPAPI win32k lockdown.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 44c81f001a69834b5b8df17397c2c52d0ef8f9e2..f1c2f0ece89d7261b4cb4eaac1d3160939a21d8d 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -957,6 +957,12 @@ const char kDisableLegacyIntermediateWindow[] = "disable-legacy-window";
 const char kDisableWin32kRendererLockDown[] =
     "disable-win32k-renderer-lockdown";
 
+// Enables the Win32K process mitigation policy for certain PPAPI mime
+// types. Each mime type is separated by a comma. Specify * to enable
+// the policy for all mime types.
+const char kEnableWin32kLockDownMimeTypes[] =
+    "enable-win32k-lockdown-mimetypes";
+
 // Enables experimental hardware acceleration for VP8/VP9 video decoding.
 const char kEnableAcceleratedVpxDecode[] = "enable-accelerated-vpx-decode";