Add IPC messages to transfer compositor protos

- Be able to send and receive compositor protos to/from the render
  process and the browser process.  Messages are piped through the
  browser process to/from the network and renderer.  A separate client
  (go/blimp) will render the compositor protos.  This is part of the
  compositor refactor around splitting ThreadProxy into two components.
- Hook the proto sending into the BlimpEngineSession class.
- Set up a RemoteProtoChannel interface on the CC side to be used by the
  ChannelMain class once we start building that from the LayerTreeHost.

BUG=552055
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1442853005

Cr-Commit-Position: refs/heads/master@{#360452}

2 files changed, 10 insertions, 1 deletions

diff --git a/blimp/engine/browser/blimp_engine_session.cc b/blimp/engine/browser/blimp_engine_session.cc
index f65706a..8f2f1c4 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);
diff --git a/blimp/engine/browser/blimp_engine_session.h b/blimp/engine/browser/blimp_engine_session.h
index 8adaef5..6b117a9 100644
--- a/blimp/engine/browser/blimp_engine_session.h
+++ b/blimp/engine/browser/blimp_engine_session.h
@@ -86,6 +86,7 @@ class BlimpEngineSession : public BlimpMessageProcessor,
                           bool last_unlocked_by_target) override;
   void CloseContents(content::WebContents* source) override;
   void ActivateContents(content::WebContents* contents) override;
+  void ForwardCompositorProto(const std::vector<uint8_t>& proto) override;
 
   // Sets up and owns |new_contents|.
   void PlatformSetContents(scoped_ptr<content::WebContents> new_contents);