cc: Always use invalidation on the pending tree when deciding to share

cc/layers/picture_layer_impl.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/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 
@@ skipping 614 matching lines @@
       tiling->contents_scale(),
       id(),
       layer_tree_impl()->source_frame_number(),
       flags);
 }
 
 PicturePileImpl* PictureLayerImpl::GetPile() {
   return pile_.get();
 }
 
-const Region* PictureLayerImpl::GetInvalidation() {
-  return &invalidation_;
+const Region* PictureLayerImpl::GetPendingInvalidation() {
+  if (layer_tree_impl()->IsPendingTree())
+    return &invalidation_;
+  DCHECK(layer_tree_impl()->IsActiveTree());
+  if (PictureLayerImpl* twin_layer = GetTwinLayer())
+    return &twin_layer->invalidation_;
+  return nullptr;
 }
 
 const PictureLayerTiling* PictureLayerImpl::GetTwinTiling(
     const PictureLayerTiling* tiling) const {
   if (!twin_layer_)
     return nullptr;
   return twin_layer_->tilings_->TilingAtScale(tiling->contents_scale());
 }
 
 PictureLayerTiling* PictureLayerImpl::GetRecycledTwinTiling(
@@ skipping 1029 matching lines @@
       PictureLayerTilingSet::TilingRange tiling_range = CurrentTilingRange();
       size_t current_tiling_range_offset = current_tiling_ - tiling_range.start;
       return tiling_range.end - 1 - current_tiling_range_offset;
     }
   }
   NOTREACHED();
   return 0;
 }
 
 }  // namespace cc