cc: Fix low-res impl-side painting artifacts

cc/picture_layer.cc

 // Copyright 2012 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/picture_layer.h"
 
 #include "cc/layer_tree_impl.h"
 #include "cc/picture_layer_impl.h"
 #include "ui/gfx/rect_conversions.h"
 
@@ skipping 25 matching lines @@
   PictureLayerImpl* layer_impl = static_cast<PictureLayerImpl*>(base_layer);
   layer_impl->SetIsMask(is_mask_);
   layer_impl->tilings_.SetLayerBounds(bounds());
   layer_impl->invalidation_.Clear();
   layer_impl->invalidation_.Swap(pile_invalidation_);
   pile_.PushPropertiesTo(layer_impl->pile_);
 
   layer_impl->SyncFromActiveLayer();
 }
 
+void PictureLayer::setLayerTreeHost(LayerTreeHost* host) {
+  Layer::setLayerTreeHost(host);
+  if (host)
+      pile_.SetMinContentsScale(host->settings().minimumContentsScale);
+}
+
 void PictureLayer::setNeedsDisplayRect(const gfx::RectF& layer_rect) {
   gfx::Rect rect = gfx::ToEnclosedRect(layer_rect);
   pending_invalidation_.Union(rect);
   Layer::setNeedsDisplayRect(layer_rect);
 }
 
 void PictureLayer::update(ResourceUpdateQueue&, const OcclusionTracker*,
                     RenderingStats& stats) {
   if (pile_.size() == bounds() && pending_invalidation_.IsEmpty())
     return;
 
   pile_.Resize(bounds());
 
   // Calling paint in WebKit can sometimes cause invalidations, so save
   // off the invalidation prior to calling update.
   pile_invalidation_.Swap(pending_invalidation_);
   pending_invalidation_.Clear();
 
   pile_.Update(client_, pile_invalidation_, stats);
 }
 
 void PictureLayer::setIsMask(bool is_mask) {
   is_mask_ = is_mask;
 }
 
 }  // namespace cc