Mac: Use 512x512 tiles by default when on high DPI devices

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index 7828dcb25cf0abd9c8d1b5d258233e7ef7c4d80b..e3ba14cd8615db255b31b0944520836e7304712f 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -178,7 +178,7 @@ gfx::Size CalculateDefaultTileSize(float initial_device_scale_factor) {
     if (numTiles >= 40)
       default_tile_size = 512;
   }
-#elif defined(OS_CHROMEOS)
+#elif defined(OS_CHROMEOS) || defined(OS_MACOSX)
   // Use 512 for high DPI (dsf=2.0f) devices.
   if (initial_device_scale_factor >= 2.0f)
     default_tile_size = 512;