Revert 106677 (caused several PPAPI test timeouts, see http://crbug.com/101154)

ppapi/proxy/dispatcher.cc

Index: ppapi/proxy/dispatcher.cc
===================================================================
--- ppapi/proxy/dispatcher.cc	(revision 106716)
+++ ppapi/proxy/dispatcher.cc	(working copy)
@@ -21,7 +21,8 @@
                        GetInterfaceFunc local_get_interface)
     : ProxyChannel(remote_process_handle),
       disallow_trusted_interfaces_(false),  // TODO(brettw) make this settable.
-      local_get_interface_(local_get_interface) {
+      local_get_interface_(local_get_interface),
+      callback_tracker_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
 }
 
 Dispatcher::~Dispatcher() {
@@ -54,6 +55,17 @@
 }
 
 bool Dispatcher::OnMessageReceived(const IPC::Message& msg) {
+  // Control messages.
+  if (msg.routing_id() == MSG_ROUTING_CONTROL) {
+    bool handled = true;
+    IPC_BEGIN_MESSAGE_MAP(Dispatcher, msg)
+      IPC_MESSAGE_FORWARD(PpapiMsg_ExecuteCallback, &callback_tracker_,
+                          CallbackTracker::ReceiveExecuteSerializedCallback)
+      IPC_MESSAGE_UNHANDLED(handled = false)
+    IPC_END_MESSAGE_MAP()
+    return handled;
+  }
+
   if (msg.routing_id() <= 0 || msg.routing_id() >= API_ID_COUNT) {
     OnInvalidMessageReceived();
     return true;