Added support of relative mouse motion in Chromoting.

remoting/proto/event.proto

 // Copyright (c) 2012 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.
 
 // Protocol for event messages.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
@@ skipping 40 matching lines @@
   optional MouseButton button = 5;
   optional bool button_down = 6;
 
   // Mouse wheel information.
   // These values encode the number of pixels and 'ticks' of movement that
   // would result from the wheel event on the client system.
   optional float wheel_delta_x = 7;
   optional float wheel_delta_y = 8;
   optional float wheel_ticks_x = 9;
   optional float wheel_ticks_y = 10;
+
+  // Mouse movement information. Provided only when mouse lock is engaged.
+  optional int32 delta_x = 11;
+  optional int32 delta_y = 12;
 }
 
 // Defines an event that sends clipboard data between peers.
 message ClipboardEvent {
 
   // The MIME type of the data being sent.
   optional string mime_type = 1;
 
   // The data being sent.
   optional bytes data = 2;
 }