Revert of Verify if GPU message pump is signaled when it hangs in WaitForWork

base/message_loop/message_loop.h

Index: base/message_loop/message_loop.h
diff --git a/base/message_loop/message_loop.h b/base/message_loop/message_loop.h
index 1230f4196d0799c5ed59fe4a51e320de2eb6bf88..11d87122c32e6da0624c670e48ed77fa5b6c8d6f 100644
--- a/base/message_loop/message_loop.h
+++ b/base/message_loop/message_loop.h
@@ -390,15 +390,6 @@
   // Runs the specified PendingTask.
   void RunTask(const PendingTask& pending_task);
 
-#if defined(OS_WIN)
-  // TODO (stanisc): crbug.com/596190: Remove this after the signaling issue
-  // has been investigated.
-  // This should be used for diagnostic only. If message pump wake-up mechanism
-  // is based on auto-reset event this call would reset the event to unset
-  // state.
-  bool MessagePumpWasSignaled();
-#endif
-
   //----------------------------------------------------------------------------
  protected:
   std::unique_ptr<MessagePump> pump_;