Photo Picker dialog: Add a test.

chrome/android/java/src/org/chromium/chrome/browser/photo_picker/PhotoPickerDialog.java

 // 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.photo_picker;
 
 import android.content.Context;
 import android.os.Bundle;
+import android.support.annotation.Nullable;
 import android.support.v7.app.AlertDialog;
 import android.view.ViewGroup.LayoutParams;
 import android.view.WindowManager;
 
+import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.R;
 import org.chromium.ui.PhotoPickerListener;
 
+import java.util.List;
+
 /**
  * UI for the photo chooser that shows on the Android platform as a result of
  * <input type=file accept=image > form element.
  */
 public class PhotoPickerDialog extends AlertDialog {
     // The category we're showing photos for.
     private PickerCategoryView mCategoryView;
 
     /**
      * The PhotoPickerDialog constructor.
      * @param context The context to use.
      * @param listener The listener object that gets notified when an action is taken.
      * @param multiSelectionAllowed Whether the photo picker should allow multiple items to be
      *                              selected.
+     * @param testFiles A list of photos to show (testing use only).
      */
-    public PhotoPickerDialog(
-            Context context, PhotoPickerListener listener, boolean multiSelectionAllowed) {
+    public PhotoPickerDialog(Context context, PhotoPickerListener listener,
+            boolean multiSelectionAllowed, @Nullable List<PickerBitmap> testFiles) {

[Theresa, 2017/05/19 16:52:42]

Rather than passing test files into the constructor, a more common pattern is to
expose a static method for testing that sets a static list of files. The test
can set the list of files during setup before creating the dialog.

DownloadManagerUi#setProviderForTests() is a good example of this.

[Finnur, 2017/05/23 13:19:50]

Good idea. Thanks! Done.

         super(context, R.style.FullscreenWhite);
 
         // Initialize the main content view.
-        mCategoryView = new PickerCategoryView(context);
+        mCategoryView = new PickerCategoryView(context, testFiles);
         mCategoryView.initialize(this, listener, multiSelectionAllowed);
         setView(mCategoryView);
     }
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
         getWindow().setLayout(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
         getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                 WindowManager.LayoutParams.FLAG_FULLSCREEN);
     }
 
     @Override
     public void dismiss() {
         super.dismiss();
         mCategoryView.onDialogDismissed();
     }
+
+    @VisibleForTesting
+    public PickerCategoryView getCategoryViewForTesting() {
+        return mCategoryView;
+    }
 }