Add a basic UI to the Android Blimp client.

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;
 
-message LoadUrlMessage {
-  optional string url = 1;
-}
-
 message ControlMessage {
   enum Type {
     // Client <=> Server types.
     CREATE_TAB = 1;
     CLOSE_TAB = 2;
-    LOAD_URL = 3;
-
-    // Server => Client types.
-    // Client => Server types.
   }
   optional Type type = 1;
-
-  optional LoadUrlMessage load_url = 1000;
 }