webapps: add splashscreen for installed webapps

chrome/android/java/res/values/colors.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>
     <!-- Common colors -->
     <color name="default_text_color">#333</color>
     <color name="default_primary_color">#f2f2f2</color>
     <color name="light_normal_color">#5A5A5A</color>
@@ skipping 68 matching lines @@
     <color name="compositor_tab_title_bar_shadow_incognito">#88000000</color>
 
     <!-- First Run Experience Colors -->
     <color name="fre_text_color">#000000</color>
     <color name="fre_light_text_color">#494949</color>
     <color name="fre_title_color">#161616</color>
 
     <!-- Sad Tab colors -->
     <color name="sad_tab_header_text_color">#333333</color>
     <color name="sad_tab_body_text_color">#646464</color>
-    
+
     <!-- NTP Colors. Used on the bookmarks and recent tabs pages. -->
     <color name="ntp_bg">#fff</color>
     <color name="ntp_bg_incognito">#222</color>
     <color name="ntp_most_visited_text">#333</color>
     <color name="ntp_most_visited_bg">#f2f2f2</color>
     <color name="ntp_list_item_text">#333</color>
     <color name="ntp_list_header_text">#333</color>
     <color name="ntp_list_header_subtext">#969696</color>
     <color name="ntp_list_header_subtext_active">#7cadff</color>
 
@@ skipping 24 matching lines @@
     <color name="find_in_page_results_status_white_color">#7f7f7f</color>
     <color name="find_in_page_failed_results_status_color">#db4437</color>
 
     <!-- App Launch Colors -->
     <color name="light_background_color">#FFFFFF</color>
 
     <!-- Reader mode colors -->
     <color name="reader_mode_header_bg">#ff494949</color>
 
     <!-- WebappActivity colors -->
+    <color name="webapp_splash_default_bg">#fafafa</color>
+    <color name="webapp_splash_title">#333333</color>
     <color name="webapp_url_bar_bg">#fafafa</color>
     <color name="webapp_url_bar_separator">#e1e1e1</color>
 
     <!-- Enhanced bookmark UI colors -->
     <color name="enhanced_bookmark_detail_text">#212121</color>
     <color name="enhanced_bookmark_detail_section">#7C7B79</color>
     <color name="enhanced_bookmark_app_bar_shadow_color">#1D000000</color>
     <color name="enhanced_bookmark_selection_action_bar_background">#4F82F4</color>
     <color name="enhanced_bookmark_drawer_selected_color">#4281F4</color>
     <color name="enhanced_bookmark_drawer_selected_background_color">#F0F0F0</color>
     <color name="enhanced_bookmark_list_item_highlight_color">#804281f4</color>
     <color name="enhanced_bookmark_icon_background_color">#ff787878</color>
     <color name="enhanced_bookmark_appbar_background">@color/default_primary_color</color>
 
     <!-- Opt out promo -->
     <color name="opt_out_text_color">#646464</color>
 </resources>