exo: Only create new SurfaceLayer if layer properties change.

components/exo/sub_surface.cc

 // 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.
 
 #include "components/exo/sub_surface.h"
 
 #include "base/logging.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "components/exo/surface.h"
@@ skipping 78 matching lines @@
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // SurfaceDelegate overrides:
 
 void SubSurface::OnSurfaceCommit() {
   // Early out if commit should be synchronized with parent.
   if (IsSurfaceSynchronized())
     return;
 
+  surface_->CheckIfSurfaceHierarchyNeedsCommitToNewSurfaces();
   surface_->CommitSurfaceHierarchy();
 }
 
 bool SubSurface::IsSurfaceSynchronized() const {
   // A sub-surface is effectively synchronized if either its parent is
   // synchronized or itself is in synchronized mode.
   if (is_synchronized_)
     return true;
 
   return parent_ ? parent_->IsSynchronized() : false;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // SurfaceObserver overrides:
 
 void SubSurface::OnSurfaceDestroying(Surface* surface) {
   surface->RemoveSurfaceObserver(this);
   if (surface == parent_) {
     parent_ = nullptr;
     return;
   }
   DCHECK(surface == surface_);
   if (parent_)
     parent_->RemoveSubSurface(surface_);
   surface_ = nullptr;
 }
 
 }  // namespace exo