Convert plugin and GPU process to brokered handle duplication.

chrome/common/chrome_content_client.cc

Index: chrome/common/chrome_content_client.cc
===================================================================
--- chrome/common/chrome_content_client.cc	(revision 131361)
+++ chrome/common/chrome_content_client.cc	(working copy)
@@ -409,6 +409,14 @@
     return false;
   }
 
+  // Add policy for proxy window pump.

[cpu_(ooo_6.6-7.5), 2012/04/11 23:12:49]

what is what are we allowing to dup here? "window pump" conjures the idea of
window handles but that cannot be the case..

[jschuh, 2012/04/11 23:52:32]

It's very confusing, but it's explained here in 
WebPluginDelegateProxy::HandleInputEvent():
http://code.google.com/searchframe#OAMlx_jo-ck/src/content/renderer/webplugin...

+  if (policy->AddRule(sandbox::TargetPolicy::SUBSYS_HANDLES,
+                      sandbox::TargetPolicy::HANDLES_DUP_ANY,
+                      L"Event") != sandbox::SBOX_ALL_OK) {
+    NOTREACHED();
+    return false;
+  }
+
   // Add the policy for the pipes.
   if (policy->AddRule(sandbox::TargetPolicy::SUBSYS_NAMED_PIPES,
                       sandbox::TargetPolicy::NAMEDPIPES_ALLOW_ANY,