Revert "Enable Offline Prefetch by default."

This reverts commit 61f145b5.

Reason for revert: Offline Prefetch should not be enabled by default but instead it should be selectively enabled via Finch.

Original change's description:
> Enable Offline Prefetch by default.
> 
> Bug: 687364
> Change-Id: I4727334dcf0060b5a8202a9694e7bd60d31029ec
> Reviewed-on: https://chromium-review.googlesource.com/1105031
> Reviewed-by: Dmitry Titov <dimich@chromium.org>
> Reviewed-by: Filip Gorski <fgorski@chromium.org>
> Commit-Queue: Carlos Knippschild <carlosk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#568230}

TBR=fgorski@chromium.org,dimich@chromium.org,carlosk@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 687364
Change-Id: I2d70657feba03f695ab461caaa8384703e81c196
Reviewed-on: https://chromium-review.googlesource.com/1122936Reviewed-by: Carlos Knippschild <carlosk@chromium.org>
Commit-Queue: Carlos Knippschild <carlosk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#571931}

components/ntp_snippets/features.cc

@@ -155,7 +155,7 @@ const char kNotificationsDailyLimit[] = "daily_limit";
 const char kNotificationsIgnoredLimitParam[] = "ignored_limit";
 
 const base::Feature kKeepPrefetchedContentSuggestions{
-    "KeepPrefetchedContentSuggestions", base::FEATURE_ENABLED_BY_DEFAULT};
+    "KeepPrefetchedContentSuggestions", base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kContentSuggestionsDebugLog{
     "ContentSuggestionsDebugLog", base::FEATURE_DISABLED_BY_DEFAULT};

components/offline_pages/core/client_policy_controller_unittest.cc

@@ -237,7 +237,7 @@ TEST_F(ClientPolicyControllerTest, CheckSuggestedArticlesDefined) {
   EXPECT_TRUE(isTemporary(policy));
   EXPECT_TRUE(controller()->IsRemovedOnCacheReset(kSuggestedArticlesNamespace));
   ExpectRemovedOnCacheReset(kSuggestedArticlesNamespace, true);
-  ExpectDownloadSupport(kSuggestedArticlesNamespace, true);
+  ExpectDownloadSupport(kSuggestedArticlesNamespace, false);
   ExpectUserRequestedDownloadSupport(kSuggestedArticlesNamespace, false);
   ExpectRecentTab(kSuggestedArticlesNamespace, false);
   ExpectOnlyOriginalTab(kSuggestedArticlesNamespace, false);

components/offline_pages/core/offline_page_feature.cc

@@ -50,7 +50,7 @@ const base::Feature kBackgroundLoaderForDownloadsFeature{
     "BackgroundLoadingForDownloads", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kPrefetchingOfflinePagesFeature{
-    "OfflinePagesPrefetching", base::FEATURE_ENABLED_BY_DEFAULT};
+    "OfflinePagesPrefetching", base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kOfflinePagesCTV2Feature{"OfflinePagesCTV2",
                                              base::FEATURE_DISABLED_BY_DEFAULT};

components/offline_pages/core/offline_page_feature_unittest.cc

@@ -64,23 +64,23 @@ TEST(OfflinePageFeatureTest, OfflinePagesLoadSignalCollecting) {
 
 TEST(OfflinePageFeatureTest, OfflinePagesPrefetching) {
   // Disabled by default.
-  EXPECT_TRUE(offline_pages::IsPrefetchingOfflinePagesEnabled());
+  EXPECT_FALSE(offline_pages::IsPrefetchingOfflinePagesEnabled());
 
   // Check if helper method works correctly when the features is enabled.
   base::test::ScopedFeatureList scoped_feature_list;
-  scoped_feature_list.InitAndDisableFeature(kPrefetchingOfflinePagesFeature);
-  EXPECT_FALSE(offline_pages::IsPrefetchingOfflinePagesEnabled());
+  scoped_feature_list.InitAndEnableFeature(kPrefetchingOfflinePagesFeature);
+  EXPECT_TRUE(offline_pages::IsPrefetchingOfflinePagesEnabled());
 }
 
 TEST(OfflinePageFeatureTest, OfflinePagesPrefetchingUI) {
-  // Enabled by default.
-  EXPECT_TRUE(offline_pages::IsOfflinePagesPrefetchingUIEnabled());
+  // Disabled by default.
+  EXPECT_FALSE(offline_pages::IsOfflinePagesPrefetchingUIEnabled());
 
   // This feature is enabled by default but depends on the core prefetching
   // feature.
   base::test::ScopedFeatureList scoped_feature_list;
-  scoped_feature_list.InitAndDisableFeature(kPrefetchingOfflinePagesFeature);
-  EXPECT_FALSE(offline_pages::IsOfflinePagesPrefetchingUIEnabled());
+  scoped_feature_list.InitAndEnableFeature(kPrefetchingOfflinePagesFeature);
+  EXPECT_TRUE(offline_pages::IsOfflinePagesPrefetchingUIEnabled());
 }
 
 TEST(OfflinePageFeatureTest, OfflinePagesLimitlessPrefetching) {