Photo Picker Dialog: Add window enter animation.

chrome/android/java/res/values-v21/styles.xml

 <?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright 2014 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. -->
 
 <resources>
     <style name="RobotoMediumStyle">
         <item name="android:fontFamily">sans-serif-medium</item>
     </style>
     <!-- Preferences -->
@@ skipping 121 matching lines @@
     <style name="MainTheme.LowEnd" parent="MainTheme">
         <item name="android:popupWindowStyle">@style/ListPopupWindow.LowEnd</item>
         <item name="android:listPopupWindowStyle">@style/ListPopupWindow.LowEnd</item>
         <item name="android:spinnerStyle">@style/Spinner.LowEnd</item>
         <item name="android:autoCompleteTextViewStyle">@style/AutoCompleteTextView.LowEnd</item>
 
         <!-- Without HW acceleration the default text cursor looks weird (top
              half is way brighter than the bottom), so we use our own. -->
         <item name="android:textCursorDrawable">@drawable/text_cursor_lowend</item>
     </style>
+
+    <!-- Photo Picker animations -->
+
+    <style name="PhotoPickerDialogAnimation">
+        <item name="android:windowEnterAnimation">@anim/design_bottom_sheet_slide_in</item>

[Theresa, 2017/05/12 15:29:40]

v21 is only used on Lollipop and higher. This should be defined in v17.

+        <item name="android:windowExitAnimation">@null</item>
+    </style>
 </resources>