Add glue between the client and engine for Blimp

blimp/common/proto/control.proto

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Message definitions for browser control messages.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
+import "size.proto";
+
+package blimp;
+
 message ControlMessage {
   enum Type {
     UNKNOWN = 0;
 
     // Client <=> Server types.
     CREATE_TAB = 1;
     CLOSE_TAB = 2;
+
+    // Client => Server types.
+    SIZE = 3;
   }
+
   optional Type type = 1;
+
+  // Feature-specific messages follow.
+  // Only one of these fields may be set per ControlMessage.
+  optional SizeMessage resize = 1000;
 }