cc: Correct elastic overscroll synchronization.

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_tree.proto";
 import "layer_tree_debug_state.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 int32 source_frame_number = 3;
   optional int32 meta_information_sequence_number = 4;
   optional LayerTreeDebugState debug_state = 8;
-  optional Vector2dF elastic_overscroll = 18;
   optional bool has_gpu_rasterization_trigger = 19;
   optional bool content_is_suitable_for_gpu_rasterization = 20;
   optional int32 id = 23;
   optional bool next_commit_forces_redraw = 24;
   optional uint32 surface_client_id = 31;
   optional uint32 next_surface_sequence = 32;
   optional LayerTree layer_tree = 36;
   optional LayerUpdate layer_updates = 28;
   optional SkPictures pictures = 38;
 }