Do not trigger HTTPS Previews NavThrottle when NS and UrlLoader are on

This allows us to turn on the URLLoader feature and have it be a no-op
for clients that do not have NetworkService enabled.

Bug: 921736
Change-Id: I9ad2612cd13798b2c4362cb07fa22be06f8aa5e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1546133
Commit-Queue: Robert Ogden <robertogden@chromium.org>
Reviewed-by: Ryan Sturm <ryansturm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#646070}

chrome/browser/previews/previews_lite_page_browsertest.cc

@@ -265,9 +265,7 @@ class PreviewsLitePageServerBrowserTest
 
     if (GetParam()) {
       url_loader_feature_list_.InitWithFeatures(
-          {network::features::kNetworkService,
-           previews::features::kHTTPSServerPreviewsUsingURLLoader},
-          {});
+          {previews::features::kHTTPSServerPreviewsUsingURLLoader}, {});
     }
   }
 
@@ -888,10 +886,11 @@ IN_PROC_BROWSER_TEST_P(
     ui_test_utils::NavigateToURL(
         browser(), PreviewsLitePageNavigationThrottle::GetPreviewsURLForURL(
                        HttpsLitePageURL(kSuccess)));
-    if (!GetParam()) {
-      VerifyPreviewNotLoaded();
-    } else {
+    if (GetParam() &&
+        base::FeatureList::IsEnabled(network::features::kNetworkService)) {
       VerifyPreviewLoaded();
+    } else {
+      VerifyPreviewNotLoaded();
     }
   }
 

chrome/browser/previews/previews_lite_page_decider.cc

@@ -38,6 +38,7 @@
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_user_data.h"
 #include "net/base/net_errors.h"
+#include "services/network/public/cpp/features.h"
 
 namespace {
 const char kUserNeedsNotification[] =
@@ -191,7 +192,8 @@ PreviewsLitePageDecider::MaybeCreateThrottleFor(
   if (!handle->IsInMainFrame())
     return nullptr;
 
-  if (base::FeatureList::IsEnabled(
+  if (base::FeatureList::IsEnabled(network::features::kNetworkService) &&
+      base::FeatureList::IsEnabled(
           previews::features::kHTTPSServerPreviewsUsingURLLoader)) {
     return nullptr;
   }