[ntp][modules] Add shopping module fieldtrial_testing_config.json (reland)

This is a reland of 0b7367ff with a fix
for msan builders, which failed on the original change. See
https://ci.chromium.org/ui/p/chromium/builders/ci/Linux%20MSan%20Tests/26482/steps?succeeded=false&debug=false

Original change's info:
> Change-Id: I735506c3e0efff1f92582498400bea0a914cf215
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2566374
> Auto-Submit: Tibor Goldschwendt <tiborg@chromium.org>
> Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
> Reviewed-by: Caitlin Fischer <caitlinfischer@google.com>
> Commit-Queue: Tibor Goldschwendt <tiborg@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#833561}

TBR=caitlinfischer@chromium.org,mahmadi@chromium.org

Bug: 1110075
Change-Id: Ic311a03eb09860d0cc8b40c55f93bb97caa095bb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2576788Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Commit-Queue: Tibor Goldschwendt <tiborg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834352}

chrome/browser/ui/search/ntp_user_data_logger.cc

@@ -625,8 +625,8 @@ NTPUserDataLogger::NTPUserDataLogger(content::WebContents* contents)
     : content::WebContentsObserver(contents),
       has_emitted_(false),
       should_record_doodle_load_time_(true),
-      during_startup_(!AfterStartupTaskUtils::IsBrowserStartupComplete()) {
-}
+      modules_visible_(false),
+      during_startup_(!AfterStartupTaskUtils::IsBrowserStartupComplete()) {}
 
 // content::WebContentsObserver override
 void NTPUserDataLogger::NavigationEntryCommitted(

testing/variations/fieldtrial_testing_config.json

@@ -2304,6 +2304,25 @@
             ]
         }
     ],
+    "DesktopNtpShoppingTasksModule": [
+        {
+            "platforms": [
+                "chromeos",
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "enable_features": [
+                        "NtpModules",
+                        "NtpShoppingTasksModule"
+                    ]
+                }
+            ]
+        }
+    ],
     "DesktopTabGroupsCollapse": [
         {
             "platforms": [