Some more improvements/fixes to the VulkanViewer

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>
 
 #include "SkTypes.h"
+#include "Timer.h"
 #include "Window_win.h"
 #include "../Application.h"
 
 static char* tchar_to_utf8(const TCHAR* str) {
 #ifdef _UNICODE
     int size = WideCharToMultiByte(CP_UTF8, 0, str, wcslen(str), NULL, 0, NULL, NULL);
     char* str8 = (char*)sk_malloc_throw(size + 1);
     WideCharToMultiByte(CP_UTF8, 0, str, wcslen(str), str8, size, NULL, NULL);
     str8[size] = '\0';
     return str8;
 #else
     return _strdup(str);
 #endif
 }
 
+static double now_ms() { return SkTime::GetNSecs() * 1e-6; }
+
 // This file can work with GUI or CONSOLE subsystem types since we define _tWinMain and main().
 
 static int main_common(HINSTANCE hInstance, int show, int argc, char**argv);
 
 int APIENTRY _tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine,
                        int nCmdShow) {
 
     // convert from lpCmdLine to argc, argv.
     char* argv[4096];
     int argc = 0;
@@ skipping 16 matching lines @@
 
 int main(int argc, char**argv) {
     return main_common(GetModuleHandle(NULL), SW_SHOW, argc, argv);
 }
 
 static int main_common(HINSTANCE hInstance, int show, int argc, char**argv) {
 
     Application* app = Application::Create(argc, argv, (void*)hInstance);
 
     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);
         } 
         
-        app->onIdle(0.0f);
+        previousTime = currentTime;
+        currentTime = now_ms();
+        app->onIdle(currentTime - previousTime);
     }
 
     delete app;
 
     return (int)msg.wParam;
 }