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

base/message_loop/message_pump_win.h

Index: base/message_loop/message_pump_win.h
diff --git a/base/message_loop/message_pump_win.h b/base/message_loop/message_pump_win.h
index 84ee3cb561875f022109d3ee2c02e709e1e039ad..bf4cdaa8420b8ba3c6f2b9c81f5679a490c71138 100644
--- a/base/message_loop/message_pump_win.h
+++ b/base/message_loop/message_pump_win.h
@@ -164,13 +164,6 @@
   void ScheduleWork() override;
   void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override;
 
-  // 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 WasSignaled() override;
-
  private:
   // MessagePumpWin methods:
   void DoRunLoop() override;