cc : Stop pushing layers from hidden subtrees at commit

cc/layers/surface_layer.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.h"
 
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
@@ skipping 81 matching lines @@
 
 std::unique_ptr<LayerImpl> SurfaceLayer::CreateLayerImpl(
     LayerTreeImpl* tree_impl) {
   return SurfaceLayerImpl::Create(tree_impl, id());
 }
 
 bool SurfaceLayer::HasDrawableContent() const {
   return primary_surface_info_.is_valid() && Layer::HasDrawableContent();
 }
 
+const SurfaceId* SurfaceLayer::GetSurfaceId(LayerTreeHost* new_host) {
+  LayerTreeHost* old_host = layer_tree_host();
+  DCHECK(!old_host || !new_host ||
+         old_host->GetSettings().enable_surface_synchronization ==
+             new_host->GetSettings().enable_surface_synchronization);
+
+  bool enable_surface_synchronization;
+  if (old_host) {
+    enable_surface_synchronization =
+        old_host->GetSettings().enable_surface_synchronization;
+  } else {
+    DCHECK(new_host);
+    enable_surface_synchronization =
+        new_host->GetSettings().enable_surface_synchronization;
+  }
+
+  if (enable_surface_synchronization) {
+    if (fallback_surface_info_.is_valid())
+      return &fallback_surface_info_.id();
+  } else {
+    return &primary_surface_info_.id();
+  }
+  return nullptr;

[jaydasika, 2017/05/23 00:25:14]

Not sure if this is correct / there is a simpler way to do this. I just copied
this block from LTHI.

+}
+
 void SurfaceLayer::SetLayerTreeHost(LayerTreeHost* host) {
   if (layer_tree_host() == host) {
-    Layer::SetLayerTreeHost(host);
     return;
   }
+  const SurfaceId* surface_id = GetSurfaceId(host);
+
+  if (layer_tree_host() && surface_id) {
+    layer_tree_host()->RemoveSurfaceLayerId(*surface_id);
+  }
+
   RemoveReference(std::move(primary_reference_returner_));
   RemoveReference(std::move(fallback_reference_returner_));
   Layer::SetLayerTreeHost(host);
   if (layer_tree_host()) {
     if (primary_surface_info_.is_valid()) {
       primary_reference_returner_ = ref_factory_->CreateReference(
           layer_tree_host(), primary_surface_info_.id());
     }
     if (fallback_surface_info_.is_valid()) {
       fallback_reference_returner_ = ref_factory_->CreateReference(
           layer_tree_host(), fallback_surface_info_.id());
     }
+    if (surface_id)
+      layer_tree_host()->AddSurfaceLayerId(*surface_id);
   }
 }
 
 void SurfaceLayer::PushPropertiesTo(LayerImpl* layer) {
   Layer::PushPropertiesTo(layer);
   TRACE_EVENT0("cc", "SurfaceLayer::PushPropertiesTo");
   SurfaceLayerImpl* layer_impl = static_cast<SurfaceLayerImpl*>(layer);
   layer_impl->SetPrimarySurfaceInfo(primary_surface_info_);
   layer_impl->SetFallbackSurfaceInfo(fallback_surface_info_);
   layer_impl->SetStretchContentToFillBounds(stretch_content_to_fill_bounds_);
 }
 
 void SurfaceLayer::RemoveReference(base::Closure reference_returner) {
   if (!reference_returner)
     return;
   auto swap_promise = base::MakeUnique<SatisfySwapPromise>(
       std::move(reference_returner),
       layer_tree_host()->GetTaskRunnerProvider()->MainThreadTaskRunner());
   layer_tree_host()->GetSwapPromiseManager()->QueueSwapPromise(
       std::move(swap_promise));
 }
 
 }  // namespace cc