Prevent recreation of UI resource holder when created with resource ID

cc/layers/ui_resource_layer.cc

 // Copyright 2013 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/ui_resource_layer.h"
 
 #include "cc/layers/ui_resource_layer_impl.h"
 #include "cc/resources/prioritized_resource.h"
 #include "cc/resources/resource_update.h"
 #include "cc/resources/resource_update_queue.h"
@@ skipping 23 matching lines @@
 };
 
 class SharedUIResourceHolder : public UIResourceLayer::UIResourceHolder {
  public:
   static scoped_ptr<SharedUIResourceHolder> Create(UIResourceId id) {
     return make_scoped_ptr(new SharedUIResourceHolder(id));
   }
 
   UIResourceId id() override { return id_; }
 
+  bool NeedsRecreation() override { return true; }
+
  private:
   explicit SharedUIResourceHolder(UIResourceId id) : id_(id) {}
 
   UIResourceId id_;
 };
 
 }  // anonymous namespace
 
 UIResourceLayer::UIResourceHolder::~UIResourceHolder() {}
 
+bool UIResourceLayer::UIResourceHolder::NeedsRecreation() {
+  return false;
+}
+
 scoped_refptr<UIResourceLayer> UIResourceLayer::Create() {
   return make_scoped_refptr(new UIResourceLayer());
 }
 
 UIResourceLayer::UIResourceLayer()
     : Layer(),
       uv_top_left_(0.f, 0.f),
       uv_bottom_right_(1.f, 1.f) {
   vertex_opacity_[0] = 1.0f;
   vertex_opacity_[1] = 1.0f;
@@ skipping 41 matching lines @@
   if (host == layer_tree_host())
     return;
 
   Layer::SetLayerTreeHost(host);
 
   // Recreate the resource hold against the new LTH.
   RecreateUIResourceHolder();
 }
 
 void UIResourceLayer::RecreateUIResourceHolder() {
-  ui_resource_holder_ = nullptr;
   if (layer_tree_host() && !bitmap_.empty()) {
     ui_resource_holder_ =
         ScopedUIResourceHolder::Create(layer_tree_host(), bitmap_);
+  } else if (ui_resource_holder_.get() &&
+             ui_resource_holder_->NeedsRecreation()) {
+    ui_resource_holder_ =

[awoloszyn, 2014/10/24 14:15:13]

We should be able to do nothing in this case, since SharedUIResourceHolder just
contains an id (integer), destroying and re-creating it seem un-necessary.

[Changwan Ryu, 2014/10/27 00:57:37]

Done.

+        SharedUIResourceHolder::Create(ui_resource_holder_->id());
+  } else {
+    ui_resource_holder_ = nullptr;
   }
   UpdateDrawsContent(HasDrawableContent());
 }
 
 void UIResourceLayer::SetBitmap(const SkBitmap& skbitmap) {
   bitmap_ = skbitmap;
 
   RecreateUIResourceHolder();
   SetNeedsCommit();
 }
@@ skipping 28 matching lines @@
     gfx::Size image_size =
         layer_tree_host()->GetUIResourceSize(ui_resource_holder_->id());
     layer_impl->SetUIResourceId(ui_resource_holder_->id());
     layer_impl->SetImageBounds(image_size);
     layer_impl->SetUV(uv_top_left_, uv_bottom_right_);
     layer_impl->SetVertexOpacity(vertex_opacity_);
   }
 }
 
 }  // namespace cc