Add new NTP layout with snippet cards and hide it behind a flag

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

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsManager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsManager.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsManager.java
index 16d74ade3a6fa20d24fc1f42f006bc3241f95486..8c637b873bf80526f346ff1e151e2271dc968e49 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsManager.java
@@ -4,21 +4,12 @@
 
 package org.chromium.chrome.browser.ntp.snippets;
 
-import android.graphics.drawable.Drawable;
-import android.os.AsyncTask;
-import android.support.v7.widget.RecyclerView;
-import android.widget.ImageView;
-
-import org.chromium.base.Log;
-import org.chromium.base.StreamUtil;
+import org.chromium.chrome.browser.ntp.NewTabPageCardsManager;
+import org.chromium.chrome.browser.ntp.NewTabPageCardsManager.NewTabPageListItem;
 import org.chromium.chrome.browser.ntp.NewTabPageView.NewTabPageManager;
 import org.chromium.chrome.browser.ntp.snippets.SnippetsBridge.SnippetsObserver;
 import org.chromium.chrome.browser.profiles.Profile;
 
-import java.io.IOException;
-import java.io.InputStream;
-import java.net.MalformedURLException;
-import java.net.URL;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -26,17 +17,6 @@ import java.util.List;
  * A class that stores and manages the article snippets that will be shown on the NTP.
  */
 public class SnippetsManager {

[newt (away), 2016/03/24 19:47:39]

I still don't understand why it's useful to keep this as a separate class,
rather than combining it into NewTabPageAdapter.

This class simply listens for updates from the SnippetsBridge and then forwards
those updates to NewTabPageAdapter. This adds extra indirection and complexity
and doesn't seem to add value. Is there some way that this class does add value
that I'm not seeing?

-    private static final String TAG = "SnippetsManager";
-
-    /**
-     * Describes the header of a group of similar card snippets
-     */
-    public static final int SNIPPET_ITEM_TYPE_HEADER = 1;
-    /**
-     * Describes a single card snippet
-     */
-    public static final int SNIPPET_ITEM_TYPE_SNIPPET = 2;
-
     /**
      * Enum values for recording {@code SNIPPETS_STATE_HISTOGRAM} histogram.
      * Stored here as it is recorded in multiple places.
@@ -48,134 +28,82 @@ public class SnippetsManager {
     public static final String SNIPPETS_STATE_HISTOGRAM = "NewTabPage.Snippets.Interactions";
 
     private NewTabPageManager mNewTabPageManager;
-    private SnippetsAdapter mDataAdapter;
+    private List<NewTabPageListItem> mListSnippetItems = new ArrayList<>();
     private SnippetsBridge mSnippetsBridge;
+    private SnippetsManagerObserver mObserver;
 
-    /** Base type for anything to add to the snippets view
+    /**
+     * An observer that will be called when new snippets are downloaded
      */
-    public interface SnippetListItem {
+    public interface SnippetsManagerObserver {
         /**
-         * Returns the type of this snippet item (SNIPPET_ITEM_TYPE_HEADER or
-         * SNIPPET_ITEM_TYPE_SNIPPET). This is so we can distinguish between different elements
-         * that are held in a single RecyclerView holder.
+         * Called when a new set of snippets are downloaded.
          *
-         * @return the type of this list item.
+         * @param listSnippets the list of new snippets and headers
          */
-        public int getType();
+        public void onSnippetsReceived(List<NewTabPageListItem> listSnippets);
     }
 
-    /** Represents the data for a header of a group of snippets
+    /**
+     * Represents the data for a header of a group of snippets
      */
-    public static class SnippetHeader implements SnippetListItem {
-        public final String mRecommendationBasis;
-
-        public SnippetHeader(String recommendationBasis) {
-            mRecommendationBasis = recommendationBasis;
-        }
+    public static class SnippetHeader implements NewTabPageListItem {
+        public SnippetHeader() {}
 
         @Override
         public int getType() {
-            return SNIPPET_ITEM_TYPE_HEADER;
+            return NewTabPageCardsManager.SNIPPET_ITEM_TYPE_HEADER;
         }
     }
 
     /**
-     * Represents the data for a card snippet.
+     * Creates a SnippetManager object that will handle all receiving all the snippets data
+     *
+     * @param tabManager the tab manager to use for loading the article
+     * @param profile the Profile of the current user.
      */
-    public static class SnippetArticle implements SnippetListItem {
-        public final String mTitle;
-        public final String mPublisher;
-        public final String mPreviewText;
-        public final String mUrl;
-        public final String mThumbnailPath;
-        public final int mPosition;
-
-        private ThumbnailRenderingTask mThumbnailRenderingTask;
-
-        // Async task to create the thumbnail from a URL
-        // TODO(maybelle): This task to retrieve the thumbnail from the web is temporary while
-        // we are prototyping this feature for clank. For the real production feature, we
-        // will likely have to download/decode the thumbnail on the native side.
-        private static class ThumbnailRenderingTask extends AsyncTask<String, Void, Drawable> {
-            private ImageView mThumbnailView;
-
-            ThumbnailRenderingTask(ImageView thumbnailView) {
-                mThumbnailView = thumbnailView;
-            }
-
-            @Override
-            protected Drawable doInBackground(String... params) {
-                if (params[0].isEmpty()) return null;
-                InputStream is = null;
-                try {
-                    is = (InputStream) new URL(params[0]).getContent();
-                    return Drawable.createFromStream(is, "thumbnail");
-                } catch (MalformedURLException e) {
-                    Log.e(TAG, "Could not get image thumbnail due to malformed URL", e);
-                } catch (IOException e) {
-                    Log.e(TAG, "Could not get image thumbnail", e);
-                } finally {
-                    StreamUtil.closeQuietly(is);
-                }
-                return null;
-            }
-
-            @Override
-            protected void onPostExecute(Drawable thumbnail) {
-                mThumbnailView.setImageDrawable(thumbnail);
-            }
-        }
-
-        public SnippetArticle(String title, String publisher, String previewText, String url,
-                String thumbnailPath, int position) {
-            mTitle = title;
-            mPublisher = publisher;
-            mPreviewText = previewText;
-            mUrl = url;
-            mThumbnailPath = thumbnailPath;
-            mPosition = position;
-        }
-
-        @Override
-        public int getType() {
-            return SNIPPET_ITEM_TYPE_SNIPPET;
-        }
-
-        /**
-         * Retrieves this SnippetArticle's thumbnail asynchronously and sets it onto the given
-         * ImageView.
-         *
-         * @param view The ImageView to set the thumbnail onto.
-         */
-        public void setThumbnailOnView(ImageView view) {
-            if (mThumbnailRenderingTask != null) mThumbnailRenderingTask.cancel(true);
-
-            mThumbnailRenderingTask = new ThumbnailRenderingTask(view);
-            mThumbnailRenderingTask.executeOnExecutor(
-                    AsyncTask.THREAD_POOL_EXECUTOR, mThumbnailPath);
-        }
-    }
-
     public SnippetsManager(NewTabPageManager tabManager, Profile profile) {
         mNewTabPageManager = tabManager;
-        mDataAdapter = new SnippetsAdapter(this);
         mSnippetsBridge = new SnippetsBridge(profile, new SnippetsObserver() {
             @Override
-            public void onSnippetsAvailable(
-                    String[] titles, String[] urls, String[] thumbnailUrls, String[] previewText) {
-                List<SnippetListItem> listItems = new ArrayList<SnippetListItem>();
+            public void onSnippetsAvailable(String[] titles, String[] urls, String[] thumbnailUrls,
+                    String[] previewText, long[] timestamps) {
+                mListSnippetItems.clear();
+                if (titles.length > 0) {
+                    mListSnippetItems.add(new SnippetHeader());
+                }
                 for (int i = 0; i < titles.length; ++i) {
-                    SnippetArticle article = new SnippetArticle(
-                            titles[i], "", previewText[i], urls[i], thumbnailUrls[i], i);
-                    listItems.add(article);
+                    SnippetArticle article = new SnippetArticle(titles[i], "", previewText[i],
+                            urls[i], thumbnailUrls[i], timestamps[i], i);
+                    mListSnippetItems.add(article);
                 }
-                mDataAdapter.setSnippetListItems(listItems);
+                notifyObserver();
             }
         });
     }
 
-    public void setSnippetsView(RecyclerView mSnippetsView) {
-        mSnippetsView.setAdapter(mDataAdapter);
+    /**
+     * Sets the SnippetsManagerObserver for this class. If we currently have a set of snippets,
+     * {@link SnippetsManagerObserver#onSnippetsReceived(List)} will immediately be called on the
+     * newly set observer.
+     *
+     * @param observer the SnippetsManagerObserver to call when receiving new snippets.
+     */
+    public void setObserver(SnippetsManagerObserver observer) {
+        mObserver = observer;
+        if (mListSnippetItems != null) {
+            notifyObserver();
+        }
+    }
+
+    private void notifyObserver() {
+        if (mObserver != null) {
+            mObserver.onSnippetsReceived(mListSnippetItems);
+        }
+    }
+
+    public List<NewTabPageListItem> getSnippetItems() {
+        return mListSnippetItems;
     }
 
     public void loadUrl(String url) {