cc: Do not create separate tilings for almost equal scale factors.

cc/layers/picture_layer_impl.cc

Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index f8aa213a92596eef4bcf8a843933d4c1d6f10da2..8e2a25e260a58a43f877d8bdab62cba2fb63115f 100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -942,7 +942,10 @@ void PictureLayerImpl::RecalculateRasterScales() {
   raster_device_scale_ = ideal_device_scale_;
   raster_page_scale_ = ideal_page_scale_;
   raster_source_scale_ = ideal_source_scale_;
-  raster_contents_scale_ = ideal_contents_scale_;
+  // Get fixed precision values to avoid creating extra tilings for scales
+  // which are almost equal.
+  raster_contents_scale_ =
+      MathUtil::RoundToFixedPrecision(ideal_contents_scale_);
 
   // If we're not animating, or leaving an animation, and the
   // ideal_source_scale_ changes, then things are unpredictable, and we fix