strmbase: Get rid of the unused "hDC" field of the BaseWindow structure.

dlls/strmbase/window.c

@@ -130,8 +130,6 @@ HRESULT WINAPI BaseWindowImpl_PrepareWindow(BaseWindow *This)
 
     SetWindowLongPtrW(This->hWnd, 0, (LONG_PTR)This);
 
-    This->hDC = GetDC(This->hWnd);
-
     return S_OK;
 }
 
@@ -140,10 +138,6 @@ HRESULT WINAPI BaseWindowImpl_DoneWithWindow(BaseWindow *This)
     if (!This->hWnd)
         return S_OK;
 
-    if (This->hDC)
-        ReleaseDC(This->hWnd, This->hDC);
-    This->hDC = NULL;
-
     SendMessageW(This->hWnd, WM_CLOSE, 0, 0);
     This->hWnd = NULL;
 

include/wine/strmbase.h

@@ -359,7 +359,6 @@ typedef struct tagBaseWindow
 	HWND hWnd;
 	LONG Width;
 	LONG Height;
-	HDC hDC;
 
 	const struct BaseWindowFuncTable* pFuncsTable;
 } BaseWindow;