Add the UI for the Interests Prototype.

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

+// Copyright 2015 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.ntp;
+
+import android.content.Context;
+import android.graphics.drawable.Drawable;
+import android.util.AttributeSet;
+import android.util.LruCache;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.BaseAdapter;
+import android.widget.GridView;
+import android.widget.LinearLayout;
+
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.ntp.InterestsItemView.DrawingData;
+import org.chromium.chrome.browser.ntp.InterestsPage.InterestsListener;
+import org.chromium.chrome.browser.ntp.InterestsService.Interest;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * The user's interests, displayed with a two collumn grid view.

[Bernhard Bauer, 2015/09/29 14:33:28]

Nit: "column".

[PEConn, 2015/11/18 15:26:57]

Done.

+ */
+public class InterestsPageView extends LinearLayout {

[Bernhard Bauer, 2015/09/29 14:33:28]

Just InterestsView? InterestsPageView implies something about how it's used.

[PEConn, 2015/11/18 15:26:57]

Done.

+
+    private InterestsListener mListener;
+    private GridView mInterestsGrid;
+    private InterestsListAdapter mAdapter;

[Bernhard Bauer, 2015/09/29 14:33:28]

Make this final as well?

[PEConn, 2015/11/18 15:26:57]

Done.

+    private final LruCache<String, Drawable> mImageCache;
+    private DrawingData mDrawingData;
+
+    public InterestsPageView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        mAdapter = new InterestsListAdapter(context);
+        mImageCache = new LruCache<>(30);
+    }
+
+    public void setListener(InterestsListener listener) {
+        mListener = listener;
+    }
+
+    public void setInterests(List<Interest> interests) {
+        mAdapter.setInterests(interests);
+        mAdapter.notifyDataSetChanged();
+    }
+
+    @Override
+    protected void onFinishInflate() {
+        super.onFinishInflate();
+
+        mInterestsGrid = (GridView) findViewById(R.id.interests_list_view);
+        mInterestsGrid.setAdapter(mAdapter);
+    }
+
+    private class InterestsListAdapter extends BaseAdapter {

[newt (away), 2015/09/29 17:33:22]

Extend ArrayAdapter instead of BaseAdapter. ArrayAdapter provides most of the
methods below for you. (You also won't need to call notifyDataSetChanged()
manually after switching to ArrayAdapter)

+
+        private List<Interest> mInterests = Collections.emptyList();
+        private Context mContext = null;
+
+        public InterestsListAdapter(Context context) {
+            mContext = context;
+        }
+
+        public void setInterests(List<Interest> interests) {
+            mInterests = interests;
+        }
+
+        @Override
+        public int getCount() {
+            return mInterests.size();
+        }
+
+        @Override
+        public Object getItem(int position) {
+            return mInterests.get(position);
+        }
+
+        @Override
+        public long getItemId(int position) {
+            return position;
+        }
+
+        @Override
+        public View getView(int position, View convertView, ViewGroup parent) {
+            if (mDrawingData == null) {
+                mDrawingData = new InterestsItemView.DrawingData(getContext());
+            }
+            Interest interest = mInterests.get(position);
+
+            if (convertView instanceof InterestsItemView) {
+                InterestsItemView view = (InterestsItemView) convertView;

[Bernhard Bauer, 2015/09/29 14:33:28]

You could extract this variable and the return statement out of the if
statement, as you assign a value in both branches and return it.

[PEConn, 2015/11/18 15:26:57]

Done.

+                view.reset(interest.getName(), interest.getImageUrl());
+                return view;
+            } else {
+                InterestsItemView itemView = new InterestsItemView(mContext, interest.getName(),
+                        interest.getImageUrl(), mListener, mImageCache, mDrawingData);
+                return itemView;
+            }
+        }
+
+        @Override
+        public boolean hasStableIds() {
+            return false;
+        }
+    }
+}