Draw downloads empty view more efficiently

chrome/android/java/src/org/chromium/chrome/browser/download/ui/DownloadManagerUi.java

 // Copyright 2016 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.download.ui;
 
 import android.app.Activity;
 import android.content.ComponentName;
 import android.content.Intent;
 import android.content.res.Resources;
 import android.net.Uri;
 import android.os.AsyncTask;
 import android.os.StrictMode;
+import android.support.graphics.drawable.VectorDrawableCompat;
 import android.support.v4.view.GravityCompat;
 import android.support.v4.widget.DrawerLayout;
 import android.support.v4.widget.DrawerLayout.DrawerListener;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.RecyclerView.AdapterDataObserver;
 import android.support.v7.widget.Toolbar.OnMenuItemClickListener;
 import android.text.TextUtils;
 import android.view.Gravity;
 import android.view.LayoutInflater;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.ListView;
+import android.widget.TextView;
 
 import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.base.ContentUriUtils;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.FileUtils;
 import org.chromium.base.Log;
 import org.chromium.base.ObserverList;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.metrics.RecordUserAction;
@@ skipping 92 matching lines @@
     private final ObserverList<DownloadUiObserver> mObservers = new ObserverList<>();
     private final BackendProvider mBackendProvider;
 
     private final Activity mActivity;
     private final boolean mIsOffTheRecord;
     private final ViewGroup mMainView;
     private final DownloadManagerToolbar mToolbar;
     private final SpaceDisplay mSpaceDisplay;
     private final ListView mFilterView;
     private final RecyclerView mRecyclerView;
-    private final View mEmptyView;
+    private final TextView mEmptyView;
     private final LoadingView mLoadingView;
 
     private BasicNativePage mNativePage;
 
     private final AdapterDataObserver mAdapterObserver = new AdapterDataObserver() {
         @Override
         public void onChanged() {
             if (mHistoryAdapter.getItemCount() == 0) {
                 mEmptyView.setVisibility(View.VISIBLE);
                 mRecyclerView.setVisibility(View.GONE);
             } else {
                 mEmptyView.setVisibility(View.GONE);
                 mRecyclerView.setVisibility(View.VISIBLE);
             }
             // At inflation, the RecyclerView is set to gone, and the loading view is visible. As
             // long as the adapter data changes, we show the recycler view, and hide loading view.
             mLoadingView.hideLoadingUI();
         }
     };
 
     public DownloadManagerUi(
             Activity activity, boolean isOffTheRecord, ComponentName parentComponent) {
         mActivity = activity;
         mIsOffTheRecord = isOffTheRecord;
         mBackendProvider =
                 sProviderForTests == null ? new DownloadBackendProvider() : sProviderForTests;
 
         mMainView = (ViewGroup) LayoutInflater.from(activity).inflate(R.layout.download_main, null);
 
-        mEmptyView = mMainView.findViewById(R.id.empty_view);
+        mEmptyView = (TextView) mMainView.findViewById(R.id.empty_view);
+        mEmptyView.setCompoundDrawablesWithIntrinsicBounds(null, VectorDrawableCompat
+                .create(activity.getResources(), R.drawable.downloads_big, activity.getTheme()),
+                null, null);
         mLoadingView = (LoadingView) mMainView.findViewById(R.id.loading_view);
         mLoadingView.showLoadingUI();
 
         mHistoryAdapter = new DownloadHistoryAdapter(isOffTheRecord, parentComponent);
         mHistoryAdapter.registerAdapterDataObserver(mAdapterObserver);
         mHistoryAdapter.initialize(mBackendProvider);
         addObserver(mHistoryAdapter);
 
         mSpaceDisplay = new SpaceDisplay(mMainView, mHistoryAdapter);
         mHistoryAdapter.registerAdapterDataObserver(mSpaceDisplay);
@@ skipping 381 matching lines @@
     public DownloadHistoryAdapter getDownloadHistoryAdapterForTests() {
         return mHistoryAdapter;
     }
 
     /** Sets a BackendProvider that is used in place of a real one. */
     @VisibleForTesting
     public static void setProviderForTests(BackendProvider provider) {
         sProviderForTests = provider;
     }
 }