mac: Add a missing gl.h include for the 10.7 SDK

With this change, target 'chrome' builds with the 10.7 SDK.

BUG=136844
TEST=none

Review URL: https://chromiumcodereview.appspot.com/10823049

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148667 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/renderer_host/accelerated_surface_container_manager_mac.cc

@@ -4,6 +4,8 @@
 
 #include "content/browser/renderer_host/accelerated_surface_container_manager_mac.h"
 
+#include <OpenGL/gl.h>
+
 #include "base/logging.h"
 #include "content/browser/renderer_host/accelerated_surface_container_mac.h"
 #include "webkit/plugins/npapi/webplugin.h"