[dxgi] Forward IDXGIOutput::GetFrameStatistics to full-screen swap chain

Testing on Windows reveals that this function does not work with windowed
mode swap chains even in flip model.

src/dxgi/dxgi_output.cpp

@@ -362,31 +362,18 @@ namespace dxvk {
     if (FAILED(hr))
       return hr;
 
-    static bool s_errorShown = false;
-
-    if (!std::exchange(s_errorShown, true))
-      Logger::warn("DxgiOutput::GetFrameStatistics: Frame statistics may be inaccurate");
-
-    // Estimate vblank count based on last known display mode. Querying
-    // the display mode on every call would be prohibitively expensive.
-    auto refreshPeriod = computeRefreshPeriod(
-      monitorInfo->LastMode.RefreshRate.Numerator,
-      monitorInfo->LastMode.RefreshRate.Denominator);
-
-    // We don't really have a way to query time since boot
-    auto t1Counter = dxvk::high_resolution_clock::get_counter();
-
-    auto t0 = dxvk::high_resolution_clock::get_time_from_counter(monitorInfo->FrameStats.SyncQPCTime.QuadPart);
-    auto t1 = dxvk::high_resolution_clock::get_time_from_counter(t1Counter);
+    // Need to acquire swap chain and unlock monitor data, since querying
+    // frame statistics from the swap chain will also access monitor data.
+    Com<IDXGISwapChain> swapChain = monitorInfo->pSwapChain;
+    m_monitorInfo->ReleaseMonitorData();
 
-    pStats->PresentCount = monitorInfo->FrameStats.PresentCount;
-    pStats->PresentRefreshCount = monitorInfo->FrameStats.PresentRefreshCount;
-    pStats->SyncRefreshCount = monitorInfo->FrameStats.SyncRefreshCount + computeRefreshCount(t0, t1, refreshPeriod);
-    pStats->SyncQPCTime.QuadPart = t1Counter;
-    pStats->SyncGPUTime.QuadPart = 0;
+    // This API only works if there is a full-screen swap chain active.
+    if (swapChain == nullptr) {
+      *pStats = DXGI_FRAME_STATISTICS();
+      return S_OK;
+    }
 
-    m_monitorInfo->ReleaseMonitorData();
-    return S_OK;
+    return swapChain->GetFrameStatistics(pStats);
   }