Hold the Pepper proxy lock for all Pepper GL calls.

ppapi/proxy/plugin_dispatcher.cc

Index: ppapi/proxy/plugin_dispatcher.cc
diff --git a/ppapi/proxy/plugin_dispatcher.cc b/ppapi/proxy/plugin_dispatcher.cc
index ad3e7a066429e8197c10501680bfb414f68b5564..3a107997d3aa7c5bd8080ce71aa6edb3dccfb7c1 100644
--- a/ppapi/proxy/plugin_dispatcher.cc
+++ b/ppapi/proxy/plugin_dispatcher.cc
@@ -211,6 +211,15 @@ bool PluginDispatcher::Send(IPC::Message* msg) {
   return SendMessage(msg);
 }
 
+bool PluginDispatcher::SendAndStayLocked(IPC::Message* msg) {
+  TRACE_EVENT2("ppapi proxy", "PluginDispatcher::SendAndStayLocked",
+               "Class", IPC_MESSAGE_ID_CLASS(msg->type()),
+               "Line", IPC_MESSAGE_ID_LINE(msg->type()));
+  if (!msg->is_reply())
+    msg->set_unblock(true);
+  return SendMessage(msg);
+}
+
 bool PluginDispatcher::OnMessageReceived(const IPC::Message& msg) {
   // We need to grab the proxy lock to ensure that we don't collide with the
   // plugin making pepper calls on a different thread.