Disable the seccomp filter GPU process sandbox by default on Chrome OS.

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index 5877de57afcb80b6adf81ca59c33e6720fbc0bf1..7e8c70484e4a471136f9fe0f2df915a3d29473da 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -130,6 +130,9 @@ const char kDisableGpuSandbox[]             = "disable-gpu-sandbox";
 // Reduces the GPU process sandbox to be less strict.
 const char kReduceGpuSandbox[]              = "reduce-gpu-sandbox";
 
+// Enable the GPU process sandbox (Linux/Chrome OS only for now).
+const char kEnableGpuSandbox[]              = "enable-gpu-sandbox";
+
 // Suppresses hang monitor dialogs in renderer processes.  This may allow slow
 // unload handlers on a page to prevent the tab from closing, but the Task
 // Manager can be used to terminate the offending process in this case.