Revert of Version of MessagePumpForUI optimized for GPU process

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 ac9f68a78f501e897ffc07b973d87efd495dde64..6f4b699cefdfce5a3fac2249d6ebbcc2bf4c5bed 100644
--- a/base/message_loop/message_pump_win.h
+++ b/base/message_loop/message_pump_win.h
@@ -8,7 +8,6 @@
 #include <windows.h>
 
 #include <list>
-#include <memory>
 
 #include "base/base_export.h"
 #include "base/message_loop/message_pump.h"
@@ -23,7 +22,7 @@
 // controlling the lifetime of the message pump.
 class BASE_EXPORT MessagePumpWin : public MessagePump {
  public:
-  MessagePumpWin() : work_state_(READY), state_(NULL) {}
+  MessagePumpWin() : have_work_(0), state_(NULL) {}
 
   // MessagePump methods:
   void Run(Delegate* delegate) override;
@@ -40,23 +39,16 @@
     int run_depth;
   };
 
-  // State used with |work_state_| variable.
-  enum WorkState {
-    READY = 0,      // Ready to accept new work.
-    HAVE_WORK = 1,  // New work has been signalled.
-    WORKING = 2     // Handling the work.
-  };
-
   virtual void DoRunLoop() = 0;
   int GetCurrentDelay() const;
 
   // The time at which delayed work should run.
   TimeTicks delayed_work_time_;
 
-  // A value used to indicate if there is a kMsgDoWork message pending
+  // A boolean value used to indicate if there is a kMsgDoWork message pending
   // in the Windows Message queue.  There is at most one such message, and it
   // can drive execution of tasks when a native message pump is running.
-  LONG work_state_;
+  LONG have_work_;
 
   // State for the current invocation of Run.
   RunState* state_;
@@ -112,6 +104,9 @@
 //
 class BASE_EXPORT MessagePumpForUI : public MessagePumpWin {
  public:
+  // The application-defined code passed to the hook procedure.
+  static const int kMessageFilterCode = 0x5001;
+
   MessagePumpForUI();
   ~MessagePumpForUI() override;
 
@@ -142,35 +137,6 @@
 };
 
 //-----------------------------------------------------------------------------
-// MessagePumpForGpu is a simplified version of UI message pump that is
-// optimized for the GPU process. Unlike MessagePumpForUI it doesn't have a
-// hidden window and doesn't handle a situation where a native message pump
-// might take over message processing.
-//
-class BASE_EXPORT MessagePumpForGpu : public MessagePumpWin {
- public:
-  MessagePumpForGpu();
-  ~MessagePumpForGpu() override;
-
-  // Factory methods.
-  static void InitFactory();
-  static std::unique_ptr<MessagePump> CreateMessagePumpForGpu();
-
-  // MessagePump methods:
-  void ScheduleWork() override;
-  void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override;
-
- private:
-  // MessagePumpWin methods:
-  void DoRunLoop() override;
-
-  void WaitForWork();
-  bool ProcessMessages();
-
-  const DWORD thread_id_;
-};
-
-//-----------------------------------------------------------------------------
 // MessagePumpForIO extends MessagePumpWin with methods that are particular to a
 // MessageLoop instantiated with TYPE_IO. This version of MessagePump does not
 // deal with Windows mesagges, and instead has a Run loop based on Completion