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 118 matching lines @@
     <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_default_bg">#fafafa</color>
+    <color name="webapp_splash_title">#333333</color>

[newt (away), 2015/09/04 18:45:48]

Reuse existing colors where possible. e.g. use default_text_color instead of
adding webapp_splash_title.

[Lalit Maganti, 2015/09/04 19:12:02]

Done.

+    <color name="webapp_splash_title_light">#ffffff</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_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>
 
     <!-- Media UI Colors -->
     <color name="media_session_icon_color">#14181C</color>
 </resources>