Fixed all unused-variable Clang warnings on Windows.

ui/base/win/atl_module.h

Index: ui/base/win/atl_module.h
diff --git a/ui/base/win/atl_module.h b/ui/base/win/atl_module.h
index 1d1adb4ca185e9a251e2e9e804a6e4695f56d246..813e92d3026b9e53fad038a06f811d8bc0ce4059 100644
--- a/ui/base/win/atl_module.h
+++ b/ui/base/win/atl_module.h
@@ -28,6 +28,7 @@ static void CreateATLModuleIfNeeded() {
   if (_pAtlModule == NULL) {
     // This creates the module and automatically updates _pAtlModule.
     CR_DEFINE_STATIC_LOCAL(CComModule, module, ());
+    static_cast<void>(module);  // Suppress unused variable warnings.
   }
 }