Do not use hungarian notation for DwmGetWindowAttribute's params

See comments from:
  https://webrtc-review.googlesource.com/c/src/+/143980

Bug: chromium:978885
Change-Id: I1b2ffe36b25fe23f3a91613b048c112f10aa1f54
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/145062
Commit-Queue: Tommi <tommi@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28522}

modules/desktop_capture/win/window_capture_utils.h

diff --git a/modules/desktop_capture/win/window_capture_utils.h b/modules/desktop_capture/win/window_capture_utils.h
index f840b4e..96d5040 100644
--- a/modules/desktop_capture/win/window_capture_utils.h
+++ b/modules/desktop_capture/win/window_capture_utils.h
@@ -61,9 +61,9 @@
 
 typedef HRESULT(WINAPI* DwmIsCompositionEnabledFunc)(BOOL* enabled);
 typedef HRESULT(WINAPI* DwmGetWindowAttributeFunc)(HWND hwnd,
-                                                   DWORD dwAttribute,
-                                                   PVOID pvAttribute,
-                                                   DWORD cbAttribute);
+                                                   DWORD flag,
+                                                   PVOID result_ptr,
+                                                   DWORD result_size);
 class WindowCaptureHelperWin {
  public:
   WindowCaptureHelperWin();
@@ -85,8 +85,7 @@
   DwmGetWindowAttributeFunc dwm_get_window_attribute_func_ = nullptr;
 
   // Only used on Win10+.
-  Microsoft::WRL::ComPtr<IVirtualDesktopManager> virtual_desktop_manager_ =
-      nullptr;
+  Microsoft::WRL::ComPtr<IVirtualDesktopManager> virtual_desktop_manager_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(WindowCaptureHelperWin);
 };