WIP: Surface Synchronization System

cc/trees/layer_tree_host_impl.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1552 matching lines @@
     metadata.root_overflow_y_hidden =
         !OuterViewportScrollLayer()->user_scrollable_vertical();
   }
 
   if (GetDrawMode() == DRAW_MODE_RESOURCELESS_SOFTWARE) {
     metadata.is_resourceless_software_draw_with_scroll_or_animation =
         IsActivelyScrolling() || mutator_host_->NeedsTickAnimations();
   }
 
   for (LayerImpl* surface_layer : active_tree_->SurfaceLayers()) {
+    SurfaceLayerImpl* surface_layer_impl =
+        static_cast<SurfaceLayerImpl*>(surface_layer);
     metadata.referenced_surfaces.push_back(
-        static_cast<SurfaceLayerImpl*>(surface_layer)->surface_info().id());
+        surface_layer_impl->primary_surface_info().id());
+    if (surface_layer_impl->fallback_surface_info().id().is_valid()) {
+      metadata.referenced_surfaces.push_back(
+          surface_layer_impl->fallback_surface_info().id());
+    }
   }
   if (!InnerViewportScrollLayer())
     return metadata;
 
   metadata.root_overflow_x_hidden |=
       !InnerViewportScrollLayer()->user_scrollable_horizontal();
   metadata.root_overflow_y_hidden |=
       !InnerViewportScrollLayer()->user_scrollable_vertical();
 
   // TODO(miletus) : Change the metadata to hold ScrollOffset.
@@ skipping 2505 matching lines @@
       worker_context_visibility_ =
           worker_context->CacheController()->ClientBecameVisible();
     } else {
       worker_context->CacheController()->ClientBecameNotVisible(
           std::move(worker_context_visibility_));
     }
   }
 }
 
 }  // namespace cc