Revert of Revert of Enable display list 2D canvas by default

content/shell/app/shell_main_delegate.cc

Index: content/shell/app/shell_main_delegate.cc
diff --git a/content/shell/app/shell_main_delegate.cc b/content/shell/app/shell_main_delegate.cc
index 914c2644d6c6c6caa26ceac5d860c75e6b1e175a..2c54863d1c59ed7f9d11d5c56b07c0a3196a3b63 100644
--- a/content/shell/app/shell_main_delegate.cc
+++ b/content/shell/app/shell_main_delegate.cc
@@ -173,6 +173,10 @@
       command_line.AppendSwitch(switches::kForceTextBlobs);
     }
 
+    if (!command_line.HasSwitch(switches::kEnableDisplayList2dCanvas)) {
+      command_line.AppendSwitch(switches::kDisableDisplayList2dCanvas);
+    }
+
     command_line.AppendSwitch(switches::kEnableInbandTextTracks);
     command_line.AppendSwitch(switches::kMuteAudio);