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

content/browser/renderer_host/render_view_host_impl.cc

Index: content/browser/renderer_host/render_view_host_impl.cc
diff --git a/content/browser/renderer_host/render_view_host_impl.cc b/content/browser/renderer_host/render_view_host_impl.cc
index b2d8a02e0439f75e48e98ff3d23cb72f3c073f58..bd37a3cbb05e221e57d090cad2642c1a0d5d627b 100644
--- a/content/browser/renderer_host/render_view_host_impl.cc
+++ b/content/browser/renderer_host/render_view_host_impl.cc
@@ -380,6 +380,12 @@
   prefs.allow_file_access_from_file_urls =
       command_line.HasSwitch(switches::kAllowFileAccessFromFiles);
 
+  prefs.layer_squashing_enabled = true;
+  if (command_line.HasSwitch(switches::kEnableLayerSquashing))
+      prefs.layer_squashing_enabled = true;
+  if (command_line.HasSwitch(switches::kDisableLayerSquashing))
+      prefs.layer_squashing_enabled = false;
+
   prefs.accelerated_2d_canvas_enabled =
       GpuProcessHost::gpu_enabled() &&
       !command_line.HasSwitch(switches::kDisableAccelerated2dCanvas);