Define SK_SAVE_LAYER_BOUNDS_ARE_FILTERED for an upcoming Skia change.

cc/playback/filter_display_item.cc

Index: cc/playback/filter_display_item.cc
diff --git a/cc/playback/filter_display_item.cc b/cc/playback/filter_display_item.cc
index fbed01509c80ff21641cf5083e9321315af56329..c155b68a64259e97e466eec07a940ea15f39de6a 100644
--- a/cc/playback/filter_display_item.cc
+++ b/cc/playback/filter_display_item.cc
@@ -43,9 +43,14 @@ void FilterDisplayItem::Raster(SkCanvas* canvas,
   skia::RefPtr<SkImageFilter> image_filter =
       RenderSurfaceFilters::BuildImageFilter(
           filters_, gfx::SizeF(bounds_.width(), bounds_.height()));
+#ifdef SK_SAVE_LAYER_BOUNDS_ARE_FILTERED
+  // TODO(senorblanco): remove this once callsites updated (crbug.com/525748)
   SkRect boundaries;
   image_filter->computeFastBounds(
       SkRect::MakeWH(bounds_.width(), bounds_.height()), &boundaries);
+#else
+  SkRect boundaries = SkRect::MakeWH(bounds_.width(), bounds_.height());
+#endif
 
   SkPaint paint;
   paint.setXfermodeMode(SkXfermode::kSrcOver_Mode);