Revert of Delete the enable/disable layer squashing flags and settings.

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index ffd6a53ab4cc58973ea47bd1c4bb069dbffe7ecb..6291019f01cbfd616db39c5d69ff0b4c056d5cc1 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -1001,6 +1001,8 @@
   // Uses the mock theme engine for scrollbars.
   settings->setMockScrollbarsEnabled(prefs.mock_scrollbars_enabled);
 
+  settings->setLayerSquashingEnabled(prefs.layer_squashing_enabled);
+
   // Enable gpu-accelerated 2d canvas if requested on the command line.
   settings->setAccelerated2dCanvasEnabled(prefs.accelerated_2d_canvas_enabled);