Add check on invalid file descriptor at both broker and renderer sides.

content/renderer/pepper_plugin_delegate_impl.cc

Index: content/renderer/pepper_plugin_delegate_impl.cc
diff --git a/content/renderer/pepper_plugin_delegate_impl.cc b/content/renderer/pepper_plugin_delegate_impl.cc
index 56aa7b943deedb60c7ab35d4b1082ea71050ee0d..43b8fd4a50218178856d0e80c7263e408be985f7 100644
--- a/content/renderer/pepper_plugin_delegate_impl.cc
+++ b/content/renderer/pepper_plugin_delegate_impl.cc
@@ -480,13 +480,21 @@ BrokerDispatcherWrapper::~BrokerDispatcherWrapper() {
 bool BrokerDispatcherWrapper::Init(
     base::ProcessHandle broker_process_handle,
     const IPC::ChannelHandle& channel_handle) {
+if (channel_handle.name.empty())
+    return false;
+
+#if defined(OS_POSIX)
+  if (channel_handle.socket.fd == -1)
+    return false;
+#endif
+
   dispatcher_delegate_.reset(new DispatcherDelegate);
   dispatcher_.reset(
       new ppapi::proxy::BrokerHostDispatcher(broker_process_handle));
 
   if (!dispatcher_->InitBrokerWithChannel(dispatcher_delegate_.get(),
                                           channel_handle,
-                                          true)) {
+                                          true)) { // is_client
     dispatcher_.reset();
     dispatcher_delegate_.reset();
     return false;