[blimp] Add SkPicture caching support.

cc/proto/layer_tree_host.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.
 
 syntax = "proto2";
 
+import "display_item.proto";
 import "layer.proto";
 import "layer_selection_bound.proto";
 import "layer_tree_debug_state.proto";
 import "property_tree.proto";
 import "size.proto";
 import "vector2df.proto";
 
 package cc.proto;
 
 option optimize_for = LITE_RUNTIME;
 
+message SkPictureData {
+  optional SkPictureID id = 1;
+  optional bytes payload = 2; /* SkData */
+}
+
+message SkPictures {
+  repeated SkPictureData pictures = 1;
+}
+
 message LayerTreeHost {
   // Not all members of LayerTreeHost are serialized, as they are not helpful
   // for remote usage. See implementation of
   // cc::LayerTreeHost::ToProtobufForCommit for details.
   optional bool needs_full_tree_sync = 1;
   optional bool needs_meta_info_recomputation = 2;
   optional int32 source_frame_number = 3;
   optional int32 meta_information_sequence_number = 4;
   optional LayerNode root_layer = 5;
   optional LayerUpdate layer_updates = 6;
@@ skipping 22 matching lines @@
   optional int32 outer_viewport_scroll_layer_id = 29;
   optional LayerSelection selection = 30;
   optional PropertyTrees property_trees = 31;
   optional uint32 surface_id_namespace = 32;
   optional uint32 next_surface_sequence = 33;
   optional uint32 wheel_event_listener_properties = 34;
   optional bool have_scroll_event_handlers = 35;
   optional uint32 touch_start_or_move_event_listener_properties = 36;
   repeated int32 layers_that_should_push_properties = 37;
   optional uint32 touch_end_or_cancel_event_listener_properties = 38;
+  optional SkPictures pictures = 39;
 }