[Offline pages on the NTP] Add UMA for offline-available NTP tiles

BUG=565219

Review URL: https://codereview.chromium.org/1721753002

Cr-Commit-Position: refs/heads/master@{#377033}

chrome/android/java/src/org/chromium/chrome/browser/ntp/MostVisitedItem.java

@@ -49,6 +49,7 @@ public interface MostVisitedItemManager {
     private MostVisitedItemManager mManager;
     private String mTitle;
     private String mUrl;
+    private boolean mOfflineAvailable;
     private int mIndex;
     private int mTileType;
     private View mView;
@@ -59,12 +60,15 @@ public interface MostVisitedItemManager {
      * @param manager The NewTabPageManager used to handle clicks and context menu events.
      * @param title The title of the page.
      * @param url The URL of the page.
+     * @param offlineAvailable Whether there is an offline copy of the URL available.
      * @param index The index of this item in the list of most visited items.
      */
-    public MostVisitedItem(MostVisitedItemManager manager, String title, String url, int index) {
+    public MostVisitedItem(MostVisitedItemManager manager, String title, String url,
+            boolean offlineAvailable, int index) {
         mManager = manager;
         mTitle = title;
         mUrl = url;
+        mOfflineAvailable = offlineAvailable;
         mIndex = index;
         mTileType = MostVisitedTileType.NONE;
     }
@@ -101,6 +105,13 @@ public String getTitle() {
         return mTitle;
     }
 
+    /**
+     * @return Whether this item is available offline.
+     */
+    public boolean isOfflineAvailable() {
+        return mOfflineAvailable;
+    }
+
     /**
      * @return The index of this MostVisitedItem in the list of MostVisitedItems.
      */

chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPage.java

@@ -529,6 +529,16 @@ public void onLoadingComplete(MostVisitedItem[] items) {
             }
             mMostVisitedSites.recordTileTypeMetrics(tileTypes);
 
+            if (isNtpOfflinePagesEnabled()) {
+                final int maxNumTiles = 12;
+                for (int i = 0; i < items.length; i++) {
+                    if (items[i].isOfflineAvailable()) {
+                        RecordHistogram.recordEnumeratedHistogram(
+                                "NewTabPage.TileOfflineAvailable", i, maxNumTiles);
+                    }
+                }
+            }
+
             SyncSessionsMetrics.recordYoungestForeignTabAgeOnNTP();
         }
     };

chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java

@@ -783,13 +783,15 @@ public void onMostVisitedURLsAvailable(String[] titles, String[] urls) {
         for (int i = 0; i < titles.length; i++) {
             final String url = urls[i];
             final String title = titles[i];
+            boolean offlineAvailable = mManager.isOfflineAvailable(url);
 
             // Look for an existing item to reuse.
             MostVisitedItem item = null;
             for (int j = 0; j < oldItemCount; j++) {
                 MostVisitedItem oldItem = oldItems[j];
                 if (oldItem != null && TextUtils.equals(url, oldItem.getUrl())
-                        && TextUtils.equals(title, oldItem.getTitle())) {
+                        && TextUtils.equals(title, oldItem.getTitle())
+                        && offlineAvailable == oldItem.isOfflineAvailable()) {
                     item = oldItem;
                     item.setIndex(i);
                     oldItems[j] = null;
@@ -799,10 +801,9 @@ public void onMostVisitedURLsAvailable(String[] titles, String[] urls) {
 
             // If nothing can be reused, create a new item.
             if (item == null) {
-                String displayTitle = getTitleForDisplay(title, url);
-                item = new MostVisitedItem(mManager, title, url, i);
-                View view = mMostVisitedDesign.createMostVisitedItemView(inflater, url,
-                        displayTitle, item, isInitialLoad);
+                item = new MostVisitedItem(mManager, title, url, offlineAvailable, i);
+                View view =
+                        mMostVisitedDesign.createMostVisitedItemView(inflater, item, isInitialLoad);
                 item.initView(view);
             }
 
@@ -963,17 +964,16 @@ public void onLargeIconAvailable(Bitmap icon, int fallbackColor) {
             }
         }
 
-        public View createMostVisitedItemView(LayoutInflater inflater, final String url,
-                String displayTitle, MostVisitedItem item,
-                final boolean isInitialLoad) {
+        public View createMostVisitedItemView(
+                LayoutInflater inflater, MostVisitedItem item, boolean isInitialLoad) {
             final MostVisitedItemView view = (MostVisitedItemView) inflater.inflate(
                     R.layout.most_visited_item, mMostVisitedLayout, false);
-            view.setTitle(displayTitle);
-            view.setOfflineAvailable(mManager.isOfflineAvailable(url));
+            view.setTitle(getTitleForDisplay(item.getTitle(), item.getUrl()));
+            view.setOfflineAvailable(item.isOfflineAvailable());
 
             LargeIconCallback iconCallback = new LargeIconCallbackImpl(item, isInitialLoad);
             if (isInitialLoad) mPendingLoadTasks++;
-            mManager.getLargeIconForUrl(url, mMinIconSize, iconCallback);
+            mManager.getLargeIconForUrl(item.getUrl(), mMinIconSize, iconCallback);
 
             return view;
         }

tools/metrics/histograms/histograms.xml

@@ -31342,6 +31342,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="NewTabPage.TileOfflineAvailable">
+  <owner>treib@chromium.org</owner>
+  <summary>
+    The number of times a tile was available offline, per tile index - compare
+    to the NewTabPage.SuggestionsImpression.* histograms. This is recorded when
+    the NTP finishes loading. Only measured on Android.
+  </summary>
+</histogram>
+
 <histogram name="NewTabPage.TileType" enum="MostVisitedTileType">
   <owner>newt@chromium.org</owner>
   <summary>