[GPU] Get GPU process running on the mac...

webkit/glue/webplugin.h

Index: webkit/glue/webplugin.h
===================================================================
--- webkit/glue/webplugin.h	(revision 37920)
+++ webkit/glue/webplugin.h	(working copy)
@@ -39,6 +39,15 @@
   // On Windows, this is the plugin window in the plugin process.
   // On X11, this is the XID of the plugin-side GtkPlug containing the
   // GtkSocket hosting the actual plugin window.
+  //
+  // On Mac OS X, all of the plugin types are currently "windowless"
+  // (window == 0) except for the special case of the GPU plugin,
+  // which currently performs rendering on behalf of the Pepper 3D API
+  // and WebGL. The GPU plugin uses a simple integer for the
+  // PluginWindowHandle which is used to map to a side data structure
+  // containing information about the plugin. Soon this plugin will be
+  // generalized, at which point this mechanism will be rethought or
+  // removed.
   gfx::PluginWindowHandle window;
   gfx::Rect window_rect;
   // Clip rect (include) and cutouts (excludes), relative to