clang/win: Let some chromium_code targets build with -Wextra.

media/capture/video/win/video_capture_device_factory_win.cc

Index: media/capture/video/win/video_capture_device_factory_win.cc
diff --git a/media/capture/video/win/video_capture_device_factory_win.cc b/media/capture/video/win/video_capture_device_factory_win.cc
index 5a626f8e56167e6db01bf47992bd8f7b4d70359d..1ff42d898d0c9955f4e2182538b964ecf696733f 100644
--- a/media/capture/video/win/video_capture_device_factory_win.cc
+++ b/media/capture/video/win/video_capture_device_factory_win.cc
@@ -63,9 +63,9 @@ static bool LoadMediaFoundationDlls() {
       L"%WINDIR%\\system32\\mfreadwrite.dll",
   };
 
-  for (int i = 0; i < arraysize(kMfDLLs); ++i) {
+  for (const wchar_t* kMfDLL : kMfDLLs) {
     wchar_t path[MAX_PATH] = {0};
-    ExpandEnvironmentStringsW(kMfDLLs[i], path, arraysize(path));
+    ExpandEnvironmentStringsW(kMfDLL, path, arraysize(path));
     if (!LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH))
       return false;
   }