Add IPC messages to transfer compositor protos

blimp/engine/browser/blimp_engine_session.cc

Index: blimp/engine/browser/blimp_engine_session.cc
diff --git a/blimp/engine/browser/blimp_engine_session.cc b/blimp/engine/browser/blimp_engine_session.cc
index 79c1a4042319c8756c8917f5775e40308f7322b8..0c7f6569010c99aae4bedb2113a9b110a6141453 100644
--- a/blimp/engine/browser/blimp_engine_session.cc
+++ b/blimp/engine/browser/blimp_engine_session.cc
@@ -138,7 +138,8 @@ void BlimpEngineSession::ProcessMessage(
     scoped_ptr<BlimpMessage> message,
     const net::CompletionCallback& callback) {
   DCHECK(message->type() == BlimpMessage::CONTROL ||
-         message->type() == BlimpMessage::NAVIGATION);
+      message->type() == BlimpMessage::NAVIGATION ||
+      message->type() == BlimpMessage::COMPOSITOR);
 
   if (message->type() == BlimpMessage::CONTROL) {
     switch (message->control().type()) {
@@ -233,6 +234,13 @@ void BlimpEngineSession::ActivateContents(content::WebContents* contents) {
   contents->GetRenderViewHost()->GetWidget()->Focus();
 }
 
+void BlimpEngineSession::ForwardCompositorProto(
+    const std::vector<uint8_t>& proto) {
+  // Send the compositor proto over the network layer to the client, which will
+  // apply the proto to their local compositor instance.
+  // TODO(dtrainor): Send the compositor proto.
+}
+
 void BlimpEngineSession::PlatformSetContents(
     scoped_ptr<content::WebContents> new_contents) {
   new_contents->SetDelegate(this);