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 5d1aeab7ae3456686a64df3dfd6ef11c471691c7..99303c788bf705834e2374fa1649aa26039b4eb8 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -121,6 +121,9 @@ 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 (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.