Add way to mark other Surface a predecessor for a Surface.

cc/surfaces/surface.cc

 // Copyright 2014 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.
 
 #include "cc/surfaces/surface.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 
 #include "cc/base/container_util.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/surfaces/surface_factory.h"
 #include "cc/surfaces/surface_id_allocator.h"
 #include "cc/surfaces/surface_manager.h"
 
 namespace cc {
 
 // The frame index starts at 2 so that empty frames will be treated as
 // completely damaged the first time they're drawn from.
 static const int kFrameIndexStart = 2;
 
 Surface::Surface(SurfaceId id, SurfaceFactory* factory)
     : surface_id_(id),
+      previous_frame_surface_id_(id),
       factory_(factory->AsWeakPtr()),
       frame_index_(kFrameIndexStart),
       destroyed_(false) {}
 
 Surface::~Surface() {
   ClearCopyRequests();
   if (current_frame_ && factory_) {
     ReturnedResourceArray current_resources;
     TransferableResource::ReturnResources(
         current_frame_->delegated_frame_data->resource_list,
         &current_resources);
     factory_->UnrefResources(current_resources);
   }
   if (!draw_callback_.is_null())
     draw_callback_.Run(SurfaceDrawStatus::DRAW_SKIPPED);
 }
 
+void Surface::SetPreviousFrameSurface(Surface* surface) {
+  DCHECK(surface);
+  frame_index_ = surface->frame_index() + 1;
+  previous_frame_surface_id_ = surface->surface_id();
+}
+
 void Surface::QueueFrame(std::unique_ptr<CompositorFrame> frame,
                          const DrawCallback& callback) {
   DCHECK(factory_);
   ClearCopyRequests();
 
   if (frame) {
     TakeLatencyInfo(&frame->metadata.latency_info);
   }
 
   std::unique_ptr<CompositorFrame> previous_frame = std::move(current_frame_);
   current_frame_ = std::move(frame);
 
   if (current_frame_) {
     factory_->ReceiveFromChild(
         current_frame_->delegated_frame_data->resource_list);
   }
 
   // Empty frames shouldn't be drawn and shouldn't contribute damage, so don't
   // increment frame index for them.
   if (current_frame_ &&
       !current_frame_->delegated_frame_data->render_pass_list.empty())
     ++frame_index_;
 
+  previous_frame_surface_id_ = surface_id();
+
   std::vector<SurfaceId> new_referenced_surfaces;
   if (current_frame_) {
     new_referenced_surfaces = current_frame_->metadata.referenced_surfaces;
   }
 
   if (previous_frame) {
     ReturnedResourceArray previous_resources;
     TransferableResource::ReturnResources(
         previous_frame->delegated_frame_data->resource_list,
         &previous_resources);
@@ skipping 104 matching lines @@
   if (current_frame_) {
     for (const auto& render_pass :
          current_frame_->delegated_frame_data->render_pass_list) {
       for (const auto& copy_request : render_pass->copy_requests)
         copy_request->SendEmptyResult();
     }
   }
 }
 
 }  // namespace cc