Serialize PictureLayer properties.

blimp/common/proto/blimp_message.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.
 //
 // Contains the BlimpMessage proto which frames all messages sent over Blimp
 // subchannels. BlimpMessage protos are serialized and transmitted over the
 // wire to the Blimplet server.
 //
 // Each BlimpMessage has a few identifying fields which provide the browser
 // session and tab ID as context. The message details are stored in a
@@ skipping 48 matching lines @@
   // then the message may have originated from a discarded session and can be
   // safely ignored.
   optional int32 session_id = 3;
 
   // ID of the tab that is referenced by this message.
   // Messages that are tab-agnostic may leave this field unset.
   optional int32 target_tab_id = 4;
 
   // Feature-specific messages follow.
   // Only one of these fields may be set per BlimpMessage.
-  // TODO(kmarshall): use a 'oneof' union when it's supported in Chromium.
+  // TODO(kmarshall): use a 'oneof' union when it's supported in Chromium.  See
+  // crbug.com/570371.
   optional ControlMessage control = 1000;
   optional NavigationMessage navigation = 1001;
   optional RenderWidgetMessage render_widget = 1002;
   optional InputMessage input = 1003;
   optional CompositorMessage compositor = 1004;
   optional ProtocolControlMessage protocol_control = 1005;
 }