More cleanup in the Vulkan viewer

tools/vulkan/win/main_win.cpp

 /*
 * Copyright 2016 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
 #include <windows.h>
 #include <tchar.h>
 
@@ skipping 54 matching lines @@
     MSG msg = { 0 };
 
     double currentTime = 0.0;
     double previousTime = 0.0;
 
     // Main message loop
     while (WM_QUIT != msg.message) {
         if (PeekMessage(&msg, nullptr, 0, 0, PM_REMOVE)) {
             TranslateMessage(&msg);
             DispatchMessage(&msg);
-        } 
-        
-        previousTime = currentTime;
-        currentTime = now_ms();
-        app->onIdle(currentTime - previousTime);
+        } else {
+            previousTime = currentTime;
+            currentTime = now_ms();
+            app->onIdle(currentTime - previousTime);
+        }
     }
 
     delete app;
 
     return (int)msg.wParam;
 }