Make partner bookmark count not skewed at zero

Record partner bookmark count as zero when skipped, so that
the distribution is not skewed.

Bug: 787132
Change-Id: Ie5c0c49120ff47a0fce984de823928997a1652f8
Reviewed-on: https://chromium-review.googlesource.com/826465Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524445}

chrome/android/java/src/org/chromium/chrome/browser/partnerbookmarks/PartnerBookmarksReader.java

@@ -155,6 +155,10 @@ public class PartnerBookmarksReader {
         }
     }
 
+    void recordPartnerBookmarkCount(int count) {
+        RecordHistogram.recordCount100Histogram("PartnerBookmark.Count2", count);
+    }
+
     /** Handles fetching partner bookmarks in a background thread. */
     private class ReadBookmarksTask extends AsyncTask<Void, Void, Void> {
         private final Object mRootSync = new Object();
@@ -163,6 +167,7 @@ public class PartnerBookmarksReader {
             SharedPreferences.Editor editor = ContextUtils.getAppSharedPreferences().edit();
             editor.putLong(LAST_EMPTY_READ_PREFS_NAME, System.currentTimeMillis());
             editor.apply();
+            recordPartnerBookmarkCount(0);
 
             Log.w(TAG,
                     "Obtained zero partner bookmarks. "
@@ -216,7 +221,7 @@ public class PartnerBookmarksReader {
             }
             bookmarkIterator.close();
             int count = urlSet.size();
-            RecordHistogram.recordCount100Histogram("PartnerBookmark.Count", count);
+            recordPartnerBookmarkCount(count);
 
             if (count == 0) {
                 handleZeroBookmark();

chrome/android/java/src/org/chromium/chrome/browser/partnerbookmarks/PartnerBookmarksShim.java

@@ -39,15 +39,19 @@ public class PartnerBookmarksShim {
 
         PartnerBookmarksReader reader = new PartnerBookmarksReader(context);
 
+        boolean systemOrPreStable =
+                (context.getApplicationInfo().flags & ApplicationInfo.FLAG_SYSTEM) == 1
+                || !ChromeVersionInfo.isStableBuild();
+        if (!systemOrPreStable) {
+            reader.onBookmarksRead();
+            return;
+        }
+
         boolean skip = shouldSkipReading();
         RecordHistogram.recordBooleanHistogram("PartnerBookmark.Skipped", skip);
         if (skip) {
             Log.i(TAG, "Skip reading partner bookmarks since recent result was empty.");
-        }
-        boolean systemOrPreStable =
-                (context.getApplicationInfo().flags & ApplicationInfo.FLAG_SYSTEM) == 1
-                || !ChromeVersionInfo.isStableBuild();
-        if (skip || !systemOrPreStable) {
+            reader.recordPartnerBookmarkCount(0);
             reader.onBookmarksRead();
             return;
         }

tools/metrics/histograms/histograms.xml

@@ -58848,6 +58848,9 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 </histogram>
 
 <histogram name="PartnerBookmark.Count" units="bookmarks">
+  <obsolete>
+    Deprecated 2017-12 by PartnerBookmark.Count2.
+  </obsolete>
   <owner>wychen@chromium.org</owner>
   <summary>
     The number of partner bookmark entries. Note that zero would be
@@ -58858,6 +58861,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="PartnerBookmark.Count2" units="bookmarks">
+  <owner>wychen@chromium.org</owner>
+  <summary>
+    The number of partner bookmark entries. Logged when using the bookmark, and
+    at most once per cold start. Note that the distribution is weighted by
+    bookmark usage.
+  </summary>
+</histogram>
+
 <histogram name="PartnerBookmark.FaviconThrottleFetchResult"
     enum="PartnerBookmark.FaviconFetchResult">
   <owner>thildebr@chromium.org</owner>