cc: Make raster source members const

cc/resources/picture_pile.h

Index: cc/resources/picture_pile.h
diff --git a/cc/resources/picture_pile.h b/cc/resources/picture_pile.h
index 8000c422d2d7ef22c9de2e8d7be6e11c236098f1..2a9a3ce6978b0e2306755231391b5b13be40907e 100644
--- a/cc/resources/picture_pile.h
+++ b/cc/resources/picture_pile.h
@@ -34,6 +34,8 @@ class CC_EXPORT PicturePile : public RecordingSource {
   gfx::Size GetSize() const final;
   void SetEmptyBounds() override;
   void SetSlowdownRasterScaleFactor(int factor) override;
+  void SetBackgroundColor(SkColor background_color) override;
+  void SetRequiresClear(bool requires_clear) override;
   bool IsSuitableForGpuRasterization() const override;
   void SetUnsuitableForGpuRasterizationForTesting() override;
   gfx::Size GetTileGridSizeForTesting() const override;
@@ -97,8 +99,11 @@ class CC_EXPORT PicturePile : public RecordingSource {
   // A hint about whether there are any recordings. This may be a false
   // positive.
   bool has_any_recordings_;
+  bool clear_canvas_with_debug_color_;
+  bool requires_clear_;
   bool is_solid_color_;
   SkColor solid_color_;
+  SkColor background_color_;
   int pixel_record_distance_;
 
  private: