[ntp] Add flag to disable the middle slot promo

Makes the middle slot promo Finch-configurable. Flag is enabled by
default.

Bug: 1166869
Change-Id: If6d4e06577f99b635f04fbe406334b66f62210b9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2638934
Commit-Queue: Esmael Elmoslimany <aee@chromium.org>
Reviewed-by: Esmael Elmoslimany <aee@chromium.org>
Auto-Submit: Tibor Goldschwendt <tiborg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845381}

chrome/browser/resources/new_tab_page/app.html

@@ -94,7 +94,9 @@
     --tile-hover-color: rgba(255, 255, 255, .1);
   }
 
-  ntp-middle-slot-promo:not([hidden]) + ntp-module-wrapper,
+  /* ~ because the dom-if results in a template between the middle-slot-promo
+     and the first ntp-module-wrapper. */
+  ntp-middle-slot-promo:not([hidden]) ~ ntp-module-wrapper,
   ntp-module-wrapper + ntp-module-wrapper {
     margin-top: 16px;
   }
@@ -266,9 +268,11 @@
             use-title-pill$="[[theme_.shortcutUseTitlePill]]">
         </ntp-most-visited>
       </template>
-      <ntp-middle-slot-promo
-          on-ntp-middle-slot-promo-loaded="onMiddleSlotPromoLoaded_">
-      </ntp-middle-slot-promo>
+      <template is="dom-if" if="[[middleSlotPromoEnabled_]]">
+        <ntp-middle-slot-promo
+            on-ntp-middle-slot-promo-loaded="onMiddleSlotPromoLoaded_">
+        </ntp-middle-slot-promo>
+      </template>
       <template is="dom-repeat" items="[[moduleDescriptors_]]" id="modules"
           on-dom-change="onModulesLoaded_">
         <ntp-module-wrapper descriptor="[[item]]"

chrome/browser/resources/new_tab_page/app.js

@@ -196,6 +196,12 @@ class AppElement extends PolymerElement {
         value: () => loadTimeData.getBoolean('shortcutsEnabled'),
       },
 
+      /** @private */
+      middleSlotPromoEnabled_: {
+        type: Boolean,
+        value: () => loadTimeData.getBoolean('middleSlotPromoEnabled'),
+      },
+
       /** @private */
       modulesEnabled_: {
         type: Boolean,
@@ -517,7 +523,8 @@ class AppElement extends PolymerElement {
    * @private
    */
   computePromoAndModulesLoaded_() {
-    return this.middleSlotPromoLoaded_ &&
+    return (!loadTimeData.getBoolean('middleSlotPromoEnabled') ||
+            this.middleSlotPromoLoaded_) &&
         (!loadTimeData.getBoolean('modulesEnabled') || this.modulesLoaded_);
   }
 

chrome/browser/ui/webui/new_tab_page/new_tab_page_ui.cc

@@ -100,6 +100,9 @@ content::WebUIDataSource* CreateNewTabPageUiHtmlSource(Profile* profile) {
       base::FeatureList::IsEnabled(ntp_features::kWebUIThemeModeDoodles));
   source->AddBoolean("shortcutsEnabled",
                      base::FeatureList::IsEnabled(ntp_features::kNtpShortcuts));
+  source->AddBoolean(
+      "middleSlotPromoEnabled",
+      base::FeatureList::IsEnabled(ntp_features::kNtpMiddleSlotPromo));
   source->AddBoolean("modulesEnabled",
                      base::FeatureList::IsEnabled(ntp_features::kModules));
   source->AddInteger("modulesLoadTimeout",

components/search/ntp_features.cc

@@ -79,6 +79,10 @@ const base::Feature kWebUIThemeModeDoodles{"WebUIThemeModeDoodles",
 const base::Feature kNtpShortcuts{"NtpShortcuts",
                                   base::FEATURE_ENABLED_BY_DEFAULT};
 
+// If enabled, middle slot promo will be shown.
+const base::Feature kNtpMiddleSlotPromo{"NtpMiddleSlotPromo",
+                                        base::FEATURE_ENABLED_BY_DEFAULT};
+
 // If enabled, modules will be shown.
 const base::Feature kModules{"NtpModules", base::FEATURE_DISABLED_BY_DEFAULT};
 

components/search/ntp_features.h

@@ -27,6 +27,7 @@ extern const base::Feature kRealboxUseGoogleGIcon;
 extern const base::Feature kWebUI;
 extern const base::Feature kWebUIThemeModeDoodles;
 extern const base::Feature kNtpShortcuts;
+extern const base::Feature kNtpMiddleSlotPromo;
 extern const base::Feature kModules;
 extern const base::Feature kNtpRecipeTasksModule;
 extern const base::Feature kNtpShoppingTasksModule;