Reserve space in the resource ID set.

cc/surfaces/surface_aggregator.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/surfaces/surface_aggregator.h"
 
 #include <map>
 
 #include "base/bind.h"
 #include "base/containers/hash_tables.h"
@@ skipping 152 matching lines @@
     const DelegatedFrameData* frame_data) {
   if (!provider_)  // TODO(jamesr): hack for unit tests that don't set up rp
     return false;
 
   int child_id = ChildIdForSurface(surface);
   if (surface->factory())
     surface->factory()->RefResources(frame_data->resource_list);
   provider_->ReceiveFromChild(child_id, frame_data->resource_list);
 
   ResourceProvider::ResourceIdSet referenced_resources;
+  size_t reserve_size =
+      std::max(static_cast<size_t>(1), frame_data->resource_list.size());

[danakj, 2015/04/25 17:16:44]

why the Max 1?

+#if defined(COMPILER_MSVC)
+  referenced_resources.reserve(reserve_size);
+#elif defined(COMPILER_GCC)
+  // Pre-standard hash-tables only implement resize, which behaves similarly

[danakj, 2015/04/25 17:16:44]

wow really? I'm surprised this is all we have in our toolchain. leave a TODO to
fix this with c++11?

can we do similar in DRLI too? that's affect children who don't use surfaces yet
(pdf viewer seems to be one eg)

+  // to reserve for these keys.
+  referenced_resources.resize(reserve_size);
+#endif
 
   bool invalid_frame = false;
   DrawQuad::ResourceIteratorCallback remap =
       base::Bind(&ValidateResourceHelper, &invalid_frame,
                  base::ConstRef(provider_->GetChildToParentMap(child_id)),
                  &referenced_resources);
   for (const auto& render_pass : frame_data->render_pass_list) {
     for (const auto& quad : render_pass->quad_list)
       quad->IterateResources(remap);
   }
@@ skipping 360 matching lines @@
 
 void SurfaceAggregator::SetFullDamageForSurface(SurfaceId surface_id) {
   auto it = previous_contained_surfaces_.find(surface_id);
   if (it == previous_contained_surfaces_.end())
     return;
   // Set the last drawn index as 0 to ensure full damage next time it's drawn.
   it->second = 0;
 }
 
 }  // namespace cc