[ViewDemotion] Create a feature flag

Add Chrome feature flag as a kill switcher.

(cherry picked from commit cda2c90)

Bug: 1448734
Change-Id: I78bcdf8d4cff389c29e753d3c783245b90ac05bf
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4564639
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Commit-Queue: Tina Wang <tinazwang@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1149216}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4574612
Cr-Commit-Position: refs/branch-heads/5790@{#171}
Cr-Branched-From: 1d71a33-refs/heads/main@{#1148114}

chrome/browser/flag-metadata.json

@@ -3212,6 +3212,11 @@
     "owners": ["clank-start","hanxi"],
     "expiry_milestone": 130
   },
+  {
+    "name": "enable-signed-out-view-demotion",
+    "owners": [ "sczs", "tinazwang" ],
+    "expiry_milestone": 135
+  },
   {
     "name": "enable-site-isolation-for-password-sites",
     "owners": [ "site-isolation-dev", "alexmos", "lukasza" ],

ios/chrome/browser/flags/about_flags.mm

@@ -1558,6 +1558,10 @@
          kHideContentSuggestionsTiles,
          kHideContentSuggestionTilesVariations,
          flag_descriptions::kHideContentSuggestionTilesName)},
+    {"enable-signed-out-view-demotion",
+     flag_descriptions::kEnableSignedOutViewDemotionName,
+     flag_descriptions::kEnableSignedOutViewDemotionDescription,
+     flags_ui::kOsIos, FEATURE_VALUE_TYPE(kEnableSignedOutViewDemotion)},
 };
 
 bool SkipConditionalFeatureEntry(const flags_ui::FeatureEntry& entry) {

ios/chrome/browser/flags/ios_chrome_flag_descriptions.cc

@@ -401,6 +401,12 @@ const char kEnableRefineDataSourceReloadReportingDescription[] =
     "Enable refining data source reload reporting when having a very short "
     "attention log";
 
+const char kEnableSignedOutViewDemotionName[] =
+    "Enable signed out user view demotion";
+const char kEnableSignedOutViewDemotionDescription[] =
+    "Enable signed out user view demotion to avoid repeated content for signed "
+    "out users.";
+
 const char kEnableSuggestionsScrollingOnIPadName[] =
     "Enable omnibox suggestions scrolling on iPad";
 const char kEnableSuggestionsScrollingOnIPadDescription[] =

ios/chrome/browser/flags/ios_chrome_flag_descriptions.h

@@ -356,6 +356,10 @@ extern const char kEnableRefineDataSourceReloadReportingDescription[];
 extern const char kEnableSuggestionsScrollingOnIPadName[];
 extern const char kEnableSuggestionsScrollingOnIPadDescription[];
 
+// Title and description for the flag to enable signed out user view demotion.
+extern const char kEnableSignedOutViewDemotionName[];
+extern const char kEnableSignedOutViewDemotionDescription[];
+
 // Title and description for the flag to enable user policies.
 extern const char kEnableUserPolicyName[];
 extern const char kEnableUserPolicyDescription[];

ios/chrome/browser/ui/ntp/new_tab_page_feature.h

@@ -61,6 +61,9 @@ BASE_DECLARE_FEATURE(kWebFeedFeedbackReroute);
 // opened.
 BASE_DECLARE_FEATURE(kEnableFollowManagementInstantReload);
 
+// Feature flag to enable signed out user view demotion.
+BASE_DECLARE_FEATURE(kEnableSignedOutViewDemotion);
+
 #pragma mark - Feature parameters
 
 // A parameter to indicate whether Reconstructed Templates is enabled for static
@@ -165,4 +168,7 @@ bool IsWebFeedFeedbackRerouteEnabled();
 // Yes when enabling follow management page instant reload when being opened.
 bool IsFollowManagementInstantReloadEnabled();
 
+// Yes if the signed out user view demotion is enabled.
+bool IsSignedOutViewDemotionEnabled();
+
 #endif  // IOS_CHROME_BROWSER_UI_NTP_NEW_TAB_PAGE_FEATURE_H_

ios/chrome/browser/ui/ntp/new_tab_page_feature.mm

@@ -71,6 +71,10 @@
              "EnableFollowManagementInstantReload",
              base::FEATURE_ENABLED_BY_DEFAULT);
 
+BASE_FEATURE(kEnableSignedOutViewDemotion,
+             "EnableSignedOutViewDemotion",
+             base::FEATURE_DISABLED_BY_DEFAULT);
+
 #pragma mark - Feature parameters
 
 const char kDiscoverFeedSRSReconstructedTemplatesEnabled[] =
@@ -200,3 +204,7 @@ bool IsWebFeedFeedbackRerouteEnabled() {
 bool IsFollowManagementInstantReloadEnabled() {
   return base::FeatureList::IsEnabled(kEnableFollowManagementInstantReload);
 }
+
+bool IsSignedOutViewDemotionEnabled() {
+  return base::FeatureList::IsEnabled(kEnableSignedOutViewDemotion);
+}