[TTS] Add Tap CTR histogram for sync-enabled users.

This adds a copy of an existing Tap CTR histogram that restricts to
sync-enabled users.  This population is an approximation of the
UKM-eligible population, which was used for training our Tap model.
This will be useful in validating CTR of the Assist Ranker Tap
Suppression experiments underway.

BUG=899135

Change-Id: Idb423da02e88c21c9123d36366de5b5f7aa5038e
Reviewed-on: https://chromium-review.googlesource.com/c/1329888Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Donn Denman <donnd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607049}

chrome/android/java/src/org/chromium/chrome/browser/contextualsearch/ContextualSearchUma.java

@@ -12,6 +12,7 @@ import org.chromium.base.metrics.RecordUserAction;
 import org.chromium.chrome.browser.compositor.bottombar.OverlayPanel.PanelState;
 import org.chromium.chrome.browser.compositor.bottombar.OverlayPanel.StateChangeReason;
 import org.chromium.chrome.browser.preferences.PrefServiceBridge;
+import org.chromium.components.sync.AndroidSyncSettings;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -824,12 +825,19 @@ public class ContextualSearchUma {
     }
 
     /**
-     * Logs whether search results were seen for a Tap gesture.  Recorded for all users.
+     * Logs whether search results were seen for a Tap gesture, for all users and sync-enabled
+     * users. For sync-enabled users we log to a separate histogram for that sub-population in order
+     * to help validate the Ranker Tap Suppression model results (since they are trained on UKM data
+     * which approximately reflects this sync-enabled population).
      * @param wasPanelSeen Whether the panel was seen.
      */
     public static void logTapResultsSeen(boolean wasPanelSeen) {
         RecordHistogram.recordBooleanHistogram(
                 "Search.ContextualSearch.Tap.ResultsSeen", wasPanelSeen);
+        if (AndroidSyncSettings.isSyncEnabled()) {
+            RecordHistogram.recordBooleanHistogram(
+                    "Search.ContextualSearch.Tap.SyncEnabled.ResultsSeen", wasPanelSeen);
+        }
     }
 
     /**

tools/metrics/histograms/histograms.xml

@@ -95947,6 +95947,18 @@ uploading your change for review.
   </summary>
 </histogram>
 
+<histogram name="Search.ContextualSearch.Tap.SyncEnabled.ResultsSeen"
+    enum="Boolean" expires_after="M76">
+  <owner>donnd@chromium.org</owner>
+  <owner>twellington@chromium.org</owner>
+  <summary>
+    Records whether the user opened the panel when it was shown for sync-enabled
+    users only (this is an approximation for the population that logs to UKM).
+    Recorded for all gestures for users with sync enabled when the UX is hidden.
+    Implemented for Android.
+  </summary>
+</histogram>
+
 <histogram name="Search.ContextualSearch.UnifiedConsent.PreviouslyUndecided"
     enum="Boolean" expires_after="2019-01-30">
   <owner>donnd@chromium.org</owner>