cc: Make separate interface for BeginFrame ipc from OutputSurface

ipc/ipc_forwarding_message_filter.cc

Index: ipc/ipc_forwarding_message_filter.cc
diff --git a/ipc/ipc_forwarding_message_filter.cc b/ipc/ipc_forwarding_message_filter.cc
index 9857bdf67dcde3b952b733dc46404162678244eb..60f56634e6e47ffddd0fdd2cc5a72df84959e600 100644
--- a/ipc/ipc_forwarding_message_filter.cc
+++ b/ipc/ipc_forwarding_message_filter.cc
@@ -23,12 +23,20 @@ ForwardingMessageFilter::ForwardingMessageFilter(
 void ForwardingMessageFilter::AddRoute(int routing_id, const Handler& handler) {
   DCHECK(!handler.is_null());
   base::AutoLock locked(handlers_lock_);
-  handlers_.insert(std::make_pair(routing_id, handler));
+  multi_handlers_.insert(std::make_pair(routing_id, handler));
 }
 
-void ForwardingMessageFilter::RemoveRoute(int routing_id) {
+void ForwardingMessageFilter::RemoveRoute(int routing_id,
+                                          const Handler& handler) {
   base::AutoLock locked(handlers_lock_);
-  handlers_.erase(routing_id);
+  auto handlers = multi_handlers_.equal_range(routing_id);
+  for (auto it = handlers.first; it != handlers.second; ++it) {
+    if (it->second.Equals(handler)) {
+      multi_handlers_.erase(it);
+      return;
+    }
+  }
+  NOTREACHED();
 }
 
 bool ForwardingMessageFilter::OnMessageReceived(const Message& message) {
@@ -36,18 +44,16 @@ bool ForwardingMessageFilter::OnMessageReceived(const Message& message) {
       message_ids_to_filter_.end())
     return false;
 
-
-  Handler handler;
-
   {
     base::AutoLock locked(handlers_lock_);
-    std::map<int, Handler>::iterator it = handlers_.find(message.routing_id());
-    if (it == handlers_.end())
+    auto handlers = multi_handlers_.equal_range(message.routing_id());
+    if (handlers.first == handlers.second)
       return false;
-    handler = it->second;
+
+    for (auto it = handlers.first; it != handlers.second; ++it)
+      target_task_runner_->PostTask(FROM_HERE, base::Bind(it->second, message));
   }
 
-  target_task_runner_->PostTask(FROM_HERE, base::Bind(handler, message));
   return true;
 }