Surface Synchronization: Distinguish between dependencies and references

cc/layers/surface_layer_impl.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/layers/surface_layer_impl.h"
 
 #include <stdint.h>
 
 #include "base/trace_event/trace_event_argument.h"
 #include "cc/debug/debug_colors.h"
@@ skipping 53 matching lines @@
 
 void SurfaceLayerImpl::AppendQuads(RenderPass* render_pass,
                                    AppendQuadsData* append_quads_data) {
   AppendRainbowDebugBorder(render_pass);
   auto* primary = CreateSurfaceDrawQuad(
       render_pass, SurfaceDrawQuadType::PRIMARY, primary_surface_info_,
       &append_quads_data->embedded_surfaces);
   // Emitting a fallback SurfaceDrawQuad is unnecessary if the primary and
   // fallback surface Ids match.
   if (primary && fallback_surface_info_.id() != primary_surface_info_.id()) {
-    primary->fallback_quad = CreateSurfaceDrawQuad(
-        render_pass, SurfaceDrawQuadType::FALLBACK, fallback_surface_info_,
-        &append_quads_data->embedded_surfaces);
+    primary->fallback_quad =
+        CreateSurfaceDrawQuad(render_pass, SurfaceDrawQuadType::FALLBACK,
+                              fallback_surface_info_, nullptr);

[vmpstr, 2017/04/11 18:35:17]

nit: comment like 

nullptr /* embedded_surfaces */);

[Fady Samuel, 2017/04/11 19:39:24]

Done.

   }
 }
 
 SurfaceDrawQuad* SurfaceLayerImpl::CreateSurfaceDrawQuad(
     RenderPass* render_pass,
     SurfaceDrawQuadType surface_draw_quad_type,
     const SurfaceInfo& surface_info,
     std::vector<SurfaceId>* embedded_surfaces) {
   if (!surface_info.is_valid())
     return nullptr;
@@ skipping 27 matching lines @@
 
   SharedQuadState* shared_quad_state =
       render_pass->CreateAndAppendSharedQuadState();
   PopulateScaledSharedQuadState(shared_quad_state, layer_to_content_scale_x,
                                 layer_to_content_scale_y);
 
   SurfaceDrawQuad* surface_draw_quad =
       render_pass->CreateAndAppendDrawQuad<SurfaceDrawQuad>();
   surface_draw_quad->SetNew(shared_quad_state, quad_rect, visible_quad_rect,
                             surface_info.id(), surface_draw_quad_type, nullptr);
-  embedded_surfaces->push_back(surface_info.id());
+  if (embedded_surfaces)
+    embedded_surfaces->push_back(surface_info.id());
 
   return surface_draw_quad;
 }
 
 void SurfaceLayerImpl::GetDebugBorderProperties(SkColor* color,
                                                 float* width) const {
   *color = DebugColors::SurfaceLayerBorderColor();
   *width = DebugColors::SurfaceLayerBorderWidth(
       layer_tree_impl() ? layer_tree_impl()->device_scale_factor() : 1);
 }
@@ skipping 90 matching lines @@
   dict->SetString("surface_id", primary_surface_info_.id().ToString());
   dict->SetString("fallback_surface_id",
                   fallback_surface_info_.id().ToString());
 }
 
 const char* SurfaceLayerImpl::LayerTypeAsString() const {
   return "cc::SurfaceLayerImpl";
 }
 
 }  // namespace cc