Avoid gpu watchdog crash on timeout if X is un-responsive.

content/gpu/gpu_watchdog_thread.h

Index: content/gpu/gpu_watchdog_thread.h
diff --git a/content/gpu/gpu_watchdog_thread.h b/content/gpu/gpu_watchdog_thread.h
index c766ca3493796949c6f8365c5f879630a8de38e0..9dd184ab32675d37d9466cd0eac732c0184b8902 100644
--- a/content/gpu/gpu_watchdog_thread.h
+++ b/content/gpu/gpu_watchdog_thread.h
@@ -12,6 +12,18 @@
 #include "base/threading/thread.h"
 #include "base/time/time.h"
 #include "content/common/gpu/gpu_watchdog.h"
+#include "ui/gfx/native_widget_types.h"
+
+#if defined(USE_X11)
+extern "C" {
+#include <X11/Xlib.h>
+#include <X11/Xatom.h>
+}
+#include <sys/poll.h>
+#include "ui/base/x/x11_util.h"
+#include "ui/gfx/x/x11_types.h"
+
+#endif
 
 namespace content {
 
@@ -62,6 +74,11 @@ class GpuWatchdogThread : public base::Thread,
   void OnAcknowledge();
   void OnCheck(bool after_suspend);
   void DeliberatelyTerminateToRecoverFromHang();
+#if defined(USE_X11)
+  void SetupXServer();
+  void SetupXChangeProp();
+  bool MatchXEventAtom(XEvent* event);
+#endif
 
   void OnAddPowerObserver();
 
@@ -93,6 +110,12 @@ class GpuWatchdogThread : public base::Thread,
   FILE* tty_file_;
 #endif
 
+#if defined(USE_X11)
+  XDisplay* display_;
+  gfx::AcceleratedWidget window_;
+  XAtom atom_;
+#endif
+
   base::WeakPtrFactory<GpuWatchdogThread> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuWatchdogThread);