cc: Workaround invalid property tree state on Layers.

cc/layers/layer_impl.h

 // 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.
 
 #ifndef CC_LAYERS_LAYER_IMPL_H_
 #define CC_LAYERS_LAYER_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 430 matching lines @@
   ElementListType GetElementTypeForAnimation() const;
 
   void set_needs_show_scrollbars(bool yes) { needs_show_scrollbars_ = yes; }
   bool needs_show_scrollbars() { return needs_show_scrollbars_; }
 
   void set_raster_even_if_not_drawn(bool yes) {
     raster_even_if_not_drawn_ = yes;
   }
   bool raster_even_if_not_drawn() const { return raster_even_if_not_drawn_; }
 
+  bool EnsureValidPropertyTreeIndices() const;

[enne (OOO), 2017/06/02 18:41:19]

bikeshed: functions called "Ensure" I expect to be void, in that they are either
asserting or silently making something valid.  This const function seems more
like a "HasValidPropertyTreeIndices".

[Khushal, 2017/06/02 18:47:03]

Done.

+
  protected:
   LayerImpl(LayerTreeImpl* layer_impl,
             int id,
             scoped_refptr<SyncedScrollOffset> scroll_offset);
   LayerImpl(LayerTreeImpl* layer_impl, int id);
 
   // Get the color and size of the layer's debug border.
   virtual void GetDebugBorderProperties(SkColor* color, float* width) const;
 
   void AppendDebugBorderQuad(RenderPass* render_pass,
@@ skipping 109 matching lines @@
   // is being animated). For this reason, while these layers are not drawn, they
   // are still rasterized.
   bool raster_even_if_not_drawn_ : 1;
 
   DISALLOW_COPY_AND_ASSIGN(LayerImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_LAYERS_LAYER_IMPL_H_