cc: Explicitly invalidate all dropped recordings on the main thread.

cc/resources/picture_pile.h

 // 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.
 
 #ifndef CC_RESOURCES_PICTURE_PILE_H_
 #define CC_RESOURCES_PICTURE_PILE_H_
 
 #include "cc/resources/picture_pile_base.h"
 #include "ui/gfx/rect.h"
 
@@ skipping 10 matching lines @@
   // Invalidations are in layer space, and will be expanded to cover everything
   // that was either recorded/changed or that has no recording, leaving out only
   // pieces that we had a recording for and it was not changed.
   // Return true iff the pile was modified.
   bool UpdateAndExpandInvalidation(
       ContentLayerClient* painter,
       Region* invalidation,
       SkColor background_color,
       bool contents_opaque,
       bool contents_fill_bounds_completely,
+      const gfx::Rect& layer_bounds_rect,
       const gfx::Rect& visible_layer_rect,
       int frame_number,
       Picture::RecordingMode recording_mode,
       RenderingStatsInstrumentation* stats_instrumentation);
 
+  void SetEmptyBoundsAndExpandInvalidation(Region* invalidation);
+
   void set_slow_down_raster_scale_factor(int factor) {
     slow_down_raster_scale_factor_for_debug_ = factor;
   }
 
   void set_show_debug_picture_borders(bool show) {
     show_debug_picture_borders_ = show;
   }
 
   bool is_suitable_for_gpu_rasterization() const {
     return is_suitable_for_gpu_rasterization_;
   }
   void SetUnsuitableForGpuRasterizationForTesting() {
     is_suitable_for_gpu_rasterization_ = false;
   }
 
  protected:
   virtual ~PicturePile();
 
  private:
   friend class PicturePileImpl;
 
   bool is_suitable_for_gpu_rasterization_;
 
   DISALLOW_COPY_AND_ASSIGN(PicturePile);
 };
 
 }  // namespace cc
 
 #endif  // CC_RESOURCES_PICTURE_PILE_H_