[Feed] Add configuration for a parity More button.

Bug: 992556
Change-Id: I6db46d4606948821a4faf30861e16180fff226c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1752164Reviewed-by: Dan H <harringtond@chromium.org>
Commit-Queue: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#686454}

chrome/android/feed/core/java/src/org/chromium/chrome/browser/feed/FeedConfiguration.java

@@ -46,6 +46,10 @@ public final class FeedConfiguration {
     /** Default value for initial non cached page size. */
     public static final long INITIAL_NON_CACHED_PAGE_SIZE_DEFAULT = 10;
 
+    private static final String LIMIT_PAGE_UPDATES_IN_HEAD = "limit_page_updates_in_head";
+    /** Default value for whether to update HEAD when making a page request. */
+    public static final boolean LIMIT_PAGE_UPDATES_IN_HEAD_DEFAULT = false;
+
     private static final String LOGGING_IMMEDIATE_CONTENT_THRESHOLD_MS =
             "logging_immediate_content_threshold_ms";
     /** Default value for logging immediate content threshold. */
@@ -151,6 +155,14 @@ public final class FeedConfiguration {
                 (int) INITIAL_NON_CACHED_PAGE_SIZE_DEFAULT);
     }
 
+    /** @return Whether to update HEAD when making a page request. */
+    @VisibleForTesting
+    static boolean getLimitPageUpdatesInHead() {
+        return ChromeFeatureList.getFieldTrialParamByFeatureAsBoolean(
+                ChromeFeatureList.INTEREST_FEED_CONTENT_SUGGESTIONS, LIMIT_PAGE_UPDATES_IN_HEAD,
+                LIMIT_PAGE_UPDATES_IN_HEAD_DEFAULT);
+    }
+
     /**
      * @return How long before showing content after opening NTP is no longer considered immediate
      *         in UMA.
@@ -290,6 +302,8 @@ public final class FeedConfiguration {
                 .put(ConfigKey.FEED_UI_ENABLED, FeedConfiguration.getFeedUiEnabled())
                 .put(ConfigKey.INITIAL_NON_CACHED_PAGE_SIZE,
                         FeedConfiguration.getInitialNonCachedPageSize())
+                .put(ConfigKey.LIMIT_PAGE_UPDATES_IN_HEAD,
+                        FeedConfiguration.getLimitPageUpdatesInHead())
                 .put(ConfigKey.LOGGING_IMMEDIATE_CONTENT_THRESHOLD_MS,
                         FeedConfiguration.getLoggingImmediateContentThresholdMs())
                 .put(ConfigKey.MANAGE_INTERESTS_ENABLED,

chrome/android/javatests/src/org/chromium/chrome/browser/feed/FeedConfigurationTest.java

@@ -46,6 +46,8 @@ public class FeedConfigurationTest {
                 FeedConfiguration.FEED_UI_ENABLED_DEFAULT, FeedConfiguration.getFeedUiEnabled());
         Assert.assertEquals(FeedConfiguration.INITIAL_NON_CACHED_PAGE_SIZE_DEFAULT,
                 FeedConfiguration.getInitialNonCachedPageSize());
+        Assert.assertEquals(FeedConfiguration.LIMIT_PAGE_UPDATES_IN_HEAD_DEFAULT,
+                FeedConfiguration.getLimitPageUpdatesInHead());
         Assert.assertEquals(FeedConfiguration.LOGGING_IMMEDIATE_CONTENT_THRESHOLD_MS_DEFAULT,
                 FeedConfiguration.getLoggingImmediateContentThresholdMs());
         Assert.assertEquals(FeedConfiguration.MANAGE_INTERESTS_ENABLED_DEFAULT,
@@ -138,6 +140,16 @@ public class FeedConfigurationTest {
         Assert.assertEquals(100, FeedConfiguration.getInitialNonCachedPageSize());
     }
 
+    @Test
+    @Feature({"Feed"})
+    @CommandLineFlags.
+    Add({"enable-features=InterestFeedContentSuggestions<Trial", "force-fieldtrials=Trial/Group",
+            "force-fieldtrial-params=Trial.Group:limit_page_updates_in_head/true"})
+    public void
+    testLimitPageUpdatesInHead() {
+        Assert.assertTrue(FeedConfiguration.getLimitPageUpdatesInHead());
+    }
+
     @Test
     @Feature({"Feed"})
     @CommandLineFlags.
@@ -294,6 +306,8 @@ public class FeedConfigurationTest {
         Assert.assertFalse(configuration.getValueOrDefault(ConfigKey.FEED_UI_ENABLED, true));
         Assert.assertEquals((long) FeedConfiguration.INITIAL_NON_CACHED_PAGE_SIZE_DEFAULT,
                 configuration.getValueOrDefault(ConfigKey.INITIAL_NON_CACHED_PAGE_SIZE, 0));
+        Assert.assertFalse(
+                configuration.getValueOrDefault(ConfigKey.LIMIT_PAGE_UPDATES_IN_HEAD, true));
         Assert.assertEquals((long) FeedConfiguration.LOGGING_IMMEDIATE_CONTENT_THRESHOLD_MS_DEFAULT,
                 configuration.getValueOrDefault(
                         ConfigKey.LOGGING_IMMEDIATE_CONTENT_THRESHOLD_MS, 0l));