Bug 1787079 - Expose gfx::GetDisplayConfig(). r=gfx-reviewers,lsalzman

We'd like to use it for changing DPI settings for the primary monitor.

Differential Revision: https://phabricator.services.mozilla.com/D156264

gfx/thebes/DisplayConfigWindows.cpp

@@ -5,9 +5,6 @@
 
 #include <iostream>
 #include <windows.h>
-#include <wingdi.h>
-#include <optional>
-#include <vector>
 
 #include "DisplayConfigWindows.h"
 
@@ -16,11 +13,6 @@ namespace gfx {
 
 using namespace std;
 
-struct DisplayConfig {
-  vector<DISPLAYCONFIG_PATH_INFO> mPaths;
-  vector<DISPLAYCONFIG_MODE_INFO> mModes;
-};
-
 optional<DisplayConfig> GetDisplayConfig() {
   LONG result;
 

gfx/thebes/DisplayConfigWindows.h

@@ -6,13 +6,23 @@
 #ifndef mozilla_gfx_thebes_DisplayConfigWindows_h
 #define mozilla_gfx_thebes_DisplayConfigWindows_h
 
-#include <utility>              // for std::pair
+#include <optional>  // for std::optional
+#include <utility>   // for std::pair
+#include <vector>    // for std::vector
+#include <wingdi.h>
 #include "mozilla/gfx/Point.h"  // for IntSize
 #include "nsTArray.h"
 
 namespace mozilla {
 namespace gfx {
 
+struct DisplayConfig {
+  std::vector<DISPLAYCONFIG_PATH_INFO> mPaths;
+  std::vector<DISPLAYCONFIG_MODE_INFO> mModes;
+};
+
+std::optional<DisplayConfig> GetDisplayConfig();
+
 extern bool HasScaledResolution();
 
 typedef nsTArray<std::pair<IntSize, IntSize>> ScaledResolutionSet;