📰 Tweak the suggestion ranks for UMA to handle fetchMore

chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsRanker.java

Index: chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsRanker.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsRanker.java b/chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsRanker.java
new file mode 100644
index 0000000000000000000000000000000000000000..49b546e42adad9266e4da3833166560b05aedcce
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/suggestions/SuggestionsRanker.java
@@ -0,0 +1,61 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.suggestions;
+
+import org.chromium.chrome.browser.ntp.cards.ActionItem;
+import org.chromium.chrome.browser.ntp.cards.SuggestionsSection;
+import org.chromium.chrome.browser.ntp.snippets.CategoryInt;
+import org.chromium.chrome.browser.ntp.snippets.SnippetArticle;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * Attributes ranks to suggestions and related elements.
+ *
+ * Ranks here are 0-based scores attributed based on the position or loading order of the
+ * elements.
+ */
+public class SuggestionsRanker {
+    private final Map<Integer, Integer> mSuggestionsAddedPerSection = new LinkedHashMap<>();
+    private int mTotalAddedSuggestions;
+
+    /**
+     * Attributes a per section rank to the provided action item.
+     * @see ActionItem#getPerSectionRank()
+     */
+    public void rankActionItem(ActionItem actionItem, SuggestionsSection section) {
+        if (actionItem.getPerSectionRank() != -1) return; // Item was already ranked.
+        actionItem.setPerSectionRank(section.getSuggestionsCount());
+    }
+
+    /**
+     * Attributes global and per section rank to the provided suggestion.
+     * @see SnippetArticle#getPerSectionRank()
+     * @see SnippetArticle#getGlobalRank()
+     */
+    public void rankSuggestion(SnippetArticle suggestion) {
+        int globalRank = mTotalAddedSuggestions++;
+        int perSectionRank = mSuggestionsAddedPerSection.get(suggestion.mCategory);
+        mSuggestionsAddedPerSection.put(suggestion.mCategory, perSectionRank + 1);
+
+        suggestion.setRank(perSectionRank, globalRank);
+    }
+
+    public void registerCategory(@CategoryInt int category) {
+        // Check we are not simply resetting an already registered category.
+        if (mSuggestionsAddedPerSection.containsKey(category)) return;
+        mSuggestionsAddedPerSection.put(category, 0);
+    }
+
+    public int getCategoryRank(@CategoryInt int category) {
+        int rank = 0;
+        for (Integer key : mSuggestionsAddedPerSection.keySet()) {
+            if (key == category) return rank;
+            ++rank;
+        }
+        return -1;
+    }
+}