cc: Reset raster scale if we didn't sync high res tiling.

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 "base/time/time.h"
@@ skipping 669 matching lines @@
       gfx::Rect layer_rect = pile_->tile_bounds(x, y);
       invalidation_.Union(layer_rect);
     }
   }
 
   // Union in the other newly exposed regions as invalid.
   Region difference_region = Region(gfx::Rect(bounds()));
   difference_region.Subtract(gfx::Rect(other->bounds()));
   invalidation_.Union(difference_region);
 
+  bool synced_high_res_tiling = false;
   if (CanHaveTilings()) {
-    tilings_->SyncTilings(
+    synced_high_res_tiling = tilings_->SyncTilings(
         *other->tilings_, bounds(), invalidation_, MinimumContentsScale());
   } else {
     RemoveAllTilings();
   }
 
-  SanityCheckTilingState();
+  // If our MinimumContentsScale has changed to prevent the twin's high res
+  // tiling from being synced, we should reset the raster scale and let it be
+  // recalculated (1) again. This can happen if our bounds shrink to the point
+  // where min contents scale grows.
+  // (1) - TODO(vmpstr) Instead of hoping that this will be recalculated, we
+  // should refactor this code a little bit and actually recalculate this.
+  // However, this is a larger undertaking, so this will work for now.
+  if (!synced_high_res_tiling)
+    ResetRasterScale();
+  else
+    SanityCheckTilingState();
 }
 
 void PictureLayerImpl::SyncTiling(
     const PictureLayerTiling* tiling) {
   if (!CanHaveTilingWithScale(tiling->contents_scale()))
     return;
   tilings_->AddTiling(tiling->contents_scale());
 
   // If this tree needs update draw properties, then the tiling will
   // get updated prior to drawing or activation.  If this tree does not
@@ skipping 849 matching lines @@
   return iterator_index_ < iterators_.size();
 }
 
 bool PictureLayerImpl::LayerEvictionTileIterator::IsCorrectType(
     PictureLayerTiling::TilingEvictionTileIterator* it) const {
   return it->get_type() == iteration_stage_ &&
          (**it)->required_for_activation() == required_for_activation_;
 }
 
 }  // namespace cc