Force use of and cache render surface.

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 818 matching lines @@
   size_t render_surface_list_size = frame->render_surface_list->size();
   for (size_t i = 0; i < render_surface_list_size; ++i) {
     size_t surface_index = render_surface_list_size - 1 - i;
     RenderSurfaceImpl* render_surface =
         (*frame->render_surface_list)[surface_index];
 
     bool is_root_surface =
         render_surface->EffectTreeIndex() == EffectTree::kContentsRootNodeId;
     bool should_draw_into_render_pass =
         is_root_surface || render_surface->contributes_to_drawn_surface() ||
-        render_surface->HasCopyRequest();
+        render_surface->HasCopyRequest() ||
+        render_surface->ForceRenderSurface();

[reveman, 2017/05/10 13:06:17]

is this needed?

[wutao, 2017/05/11 19:36:35]

Removed.

     if (should_draw_into_render_pass)
       frame->render_passes.push_back(render_surface->CreateRenderPass());
   }
 
   // Damage rects for non-root passes aren't meaningful, so set them to be
   // equal to the output rect.
   for (size_t i = 0; i + 1 < frame->render_passes.size(); ++i) {
     RenderPass* pass = frame->render_passes[i].get();
     pass->damage_rect = pass->output_rect;
   }
@@ skipping 3448 matching lines @@
 
 void LayerTreeHostImpl::ShowScrollbarsForImplScroll(ElementId element_id) {
   if (!element_id)
     return;
   if (ScrollbarAnimationController* animation_controller =
           ScrollbarAnimationControllerForElementId(element_id))
     animation_controller->DidScrollUpdate();
 }
 
 }  // namespace cc