Fix reference_wrapper bug in Android WebView cookie feature override

This fixes a bug where a base::Feature ref was implicitly converted to
reference_wrapper incorrectly, such that the feature override worked on
debug builds but not on release builds. This explicitly converts it via
std::cref, which fixes the behavior for release builds.

Bug: 986319
Change-Id: Ic2511f71d83b2c25e4a5cbf2bc8a3f205fec464e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2640921Reviewed-by: Richard Coles <torne@chromium.org>
Commit-Queue: Lily Chen <chlily@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845317}

android_webview/browser/aw_feature_list_creator.cc

@@ -110,7 +110,7 @@ GetSwitchDependentFeatureOverrides(const base::CommandLine& command_line) {
   // default.
   if (command_line.HasSwitch(switches::kWebViewEnableModernCookieSameSite)) {
     feature_overrides.push_back(
-        std::make_pair(net::features::kSchemefulSameSite,
+        std::make_pair(std::cref(net::features::kSchemefulSameSite),
                        base::FeatureList::OVERRIDE_ENABLE_FEATURE));
   }