Implement position: sticky updates on compositor

cc/proto/property_tree.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 "element_id.proto";
+import "layer_sticky_position_constraint.proto";
 import "rectf.proto";
 import "scroll_offset.proto";
 import "size.proto";
 import "skxfermode.proto";
 import "synced_property.proto";
 import "transform.proto";
 import "vector2df.proto";
 
 option optimize_for = LITE_RUNTIME;
 
@@ skipping 43 matching lines @@
 // Proto for TransformCachedNodeData
 message TransformCachedNodeData {
   optional Transform from_target = 1;
   optional Transform to_target = 2;
   optional Transform from_screen = 3;
   optional Transform to_screen = 4;
   optional int64 target_id = 5;
   optional int64 content_target_id = 6;
 }
 
+// Proto for StickyPositionNodeData
+message StickyPositionNodeData {
+  optional int64 scroll_ancestor = 1;
+  optional LayerStickyPositionConstraint constraints = 2;
+  optional Vector2dF main_thread_offset = 3;
+}
+
 // Proto for struct ClipNodeData.
 // NEXT ID: 13
 message ClipNodeData {
   optional RectF clip = 1;
   optional RectF combined_clip_in_target_space = 2;
   optional RectF clip_in_target_space = 3;
 
   optional int64 transform_id = 4;
   optional int64 target_transform_id = 5;
   optional int64 target_effect_id = 12;
@@ skipping 111 matching lines @@
 message TransformTreeData {
   optional bool source_to_parent_updates_allowed = 1;
   optional float page_scale_factor = 2;
   optional float device_scale_factor = 3;
   optional float device_transform_scale_factor = 4;
   repeated int64 nodes_affected_by_inner_viewport_bounds_delta = 7
       [packed = true];
   repeated int64 nodes_affected_by_outer_viewport_bounds_delta = 8
       [packed = true];
   repeated TransformCachedNodeData cached_data = 9;
+  repeated StickyPositionNodeData sticky_position_data = 10;
 }
 
 // Proto for data members of class EffectTree.
 message EffectTreeData {
   repeated int64 mask_replica_layer_ids = 1 [packed = true];
 }
 
 // Proto for class PropertyTrees.
 // NEXT ID: 17
 message PropertyTrees {
   optional PropertyTree transform_tree = 1;
   optional PropertyTree effect_tree = 2;
   optional PropertyTree clip_tree = 3;
   optional PropertyTree scroll_tree = 7;
 
   optional bool needs_rebuild = 4;
   optional bool non_root_surfaces_enabled = 5;
   optional bool changed = 11;
   optional bool full_tree_damaged = 12;
   optional int64 sequence_number = 6;
   optional bool is_main_thread = 13;
   optional bool is_active = 14;
   optional bool verify_transform_tree_calculations = 16;
 
   optional Vector2dF inner_viewport_container_bounds_delta = 8;
   optional Vector2dF outer_viewport_container_bounds_delta = 9;
   optional Vector2dF inner_viewport_scroll_bounds_delta = 10;
   repeated int64 always_use_active_tree_opacity_effect_ids = 15 [packed = true];
 }