Clean up recording of clicks for New tab page snippets

chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticle.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticle.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticle.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticle.java
index 9e8816656de283cdf913310e6bc11a4557cbc1e0..a2d81a1bdf3a5c9a277af5770f53d1abe4b73ab6 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticle.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetArticle.java
@@ -6,6 +6,8 @@ package org.chromium.chrome.browser.ntp.snippets;
 import android.graphics.Bitmap;
 
 import org.chromium.base.metrics.RecordHistogram;
+import org.chromium.base.metrics.RecordUserAction;
+import org.chromium.chrome.browser.ntp.NewTabPageUma;
 import org.chromium.chrome.browser.ntp.cards.NewTabPageListItem;
 
 /**
@@ -19,7 +21,7 @@ public class SnippetArticle implements NewTabPageListItem {
     public final String mUrl;
     public final String mAmpUrl;
     public final String mThumbnailUrl;
-    public final long mTimestamp;
+    public final long mPublishTimestampMilliseconds;
     public final float mScore;
     public final int mPosition;
 
@@ -29,6 +31,9 @@ public class SnippetArticle implements NewTabPageListItem {
     /** Stores whether impression of this article has been tracked already. */
     private boolean mImpressionTracked;
 
+    /** Specifies ranges of positions for which we store position-specific sub-histograms. */
+    private static final int[] HISTOGRAM_FOR_POSITIONS = {0, 2, 4, 9};
+
     /**
      * Creates a SnippetArticle object that will hold the data
      * @param title the title of the article
@@ -50,7 +55,7 @@ public class SnippetArticle implements NewTabPageListItem {
         mUrl = url;
         mAmpUrl = ampUrl;
         mThumbnailUrl = thumbnailUrl;
-        mTimestamp = timestamp;
+        mPublishTimestampMilliseconds = timestamp;
         mScore = score;
         mPosition = position;
     }
@@ -84,6 +89,30 @@ public class SnippetArticle implements NewTabPageListItem {
         mThumbnailBitmap = bitmap;
     }
 
+    /** Tracks click on this NTP snippet in UMA. */
+    public void trackClick() {
+        RecordUserAction.record("MobileNTP.Snippets.Click");
+        RecordHistogram.recordSparseSlowlyHistogram("NewTabPage.Snippets.CardClicked", mPosition);
+        NewTabPageUma.recordSnippetAction(NewTabPageUma.SNIPPETS_ACTION_CLICKED);
+        NewTabPageUma.recordAction(NewTabPageUma.ACTION_OPENED_SNIPPET);
+
+        // Track how the (approx.) position relates to age / score of the snippet that is clicked.
+        int ageInMinutes =
+                (int) ((System.currentTimeMillis() - mPublishTimestampMilliseconds) / 60000L);
+        recordAge("NewTabPage.Snippets.CardClickedAge", ageInMinutes);
+        recordScore("NewTabPage.Snippets.CardClickedScore", mScore);
+        int startPosition = 0;
+        for (int endPosition : HISTOGRAM_FOR_POSITIONS) {
+            if (mPosition >= startPosition && mPosition <= endPosition) {
+                String suffix = "_" + startPosition + "_" + endPosition;
+                recordAge("NewTabPage.Snippets.CardClickedAge" + suffix, ageInMinutes);
+                recordScore("NewTabPage.Snippets.CardClickedScore" + suffix, mScore);
+                break;
+            }
+            startPosition = endPosition + 1;
+        }
+    }
+
     /** Tracks impression of this NTP snippet. */
     public void trackImpression() {
         // Track UMA only upon the first impression per life-time of this object.
@@ -97,4 +126,18 @@ public class SnippetArticle implements NewTabPageListItem {
     public boolean impressionTracked() {
         return mImpressionTracked;
     }
+
+    private static void recordAge(String histogramName, int ageInMinutes) {
+        // Negative values (when the time of the device is set inappropriately) provide no value.
+        if (ageInMinutes >= 0) {
+            // If the max value below (72 hours) were to be changed, the histogram should be renamed
+            // since it will change the shape of buckets.
+            RecordHistogram.recordCustomCountHistogram(histogramName, ageInMinutes, 1, 72 * 60, 50);
+        }
+    }
+
+    private static void recordScore(String histogramName, float score) {
+        int recordedScore = Math.min((int) Math.ceil(score), 1000);
+        RecordHistogram.recordCount1000Histogram(histogramName, recordedScore);
+    }
 }