Revert of 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 3a107997d3aa7c5bd8080ce71aa6edb3dccfb7c1..ad3e7a066429e8197c10501680bfb414f68b5564 100644
--- a/ppapi/proxy/plugin_dispatcher.cc
+++ b/ppapi/proxy/plugin_dispatcher.cc
@@ -211,15 +211,6 @@
   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.