Add platform_app flag to manifest.

chrome/app/generated_resources.grd

 <?xml version="1.0" encoding="UTF-8"?>
 
 <!--
 This file contains definitions of resources that will be translated for each
 locale.  The variables is_win, is_macosx, is_linux, and is_posix are available
 for making strings OS specific.  Other platform defines such as use_titlecase
 are declared in build/common.gypi.
 -->
 
 <grit base_dir="." latest_public_release="0" current_release="1"
@@ skipping 4850 matching lines @@
       </message>
       <message name="IDS_FLAGS_ENABLE_MEDIA_SOURCE_DESCRIPTION" desc="Description for the flag to enable the Media Source API on &lt;video&gt; elements.">
         Enable experimental Media Source API on the video elements. This API allows JavaScript to send media data directly to a video element.
       </message>
       <message name="IDS_FLAGS_AURA_WINDOWS_NAME" desc="Title for the flag to enable fancy translucent windows.">
         Translucent windows
       </message>
       <message name="IDS_FLAGS_AURA_WINDOWS_DESCRIPTION" desc="Description for the flag to enable fancy translucent windows.">
         Enable the "Aura" style for translucent window frames and constrained window dragging.
       </message>
+      <message name="IDS_FLAGS_ENABLE_PLATFORM_APPS_NAME" desc="Title for the flag to enable platform apps.">
+        Enable platform apps
+      </message>
+      <message name="IDS_FLAGS_ENABLE_PLATFORM_APPS_DESCRIPTION" desc="Description for the flag to enable platform apps.">
+        Enable advanced application capabilities.
+      </message>
 
       <!-- Crashes -->
       <message name="IDS_CRASHES_TITLE" desc="Title for the chrome://crashes page.">
         Crashes
       </message>
       <message name="IDS_CRASHES_CRASH_COUNT_BANNER_FORMAT" desc="Format for crash count banner on chrome://crashes">
         Crashes (<ph name="CRASH_COUNT">$1<ex>3</ex></ph>)
       </message>
       <message name="IDS_CRASHES_CRASH_HEADER_FORMAT" desc="Format for crash entry headings on chrome://crashes">
         Crash ID <ph name="CRASH_ID">$1<ex>8fa95dbb6f2ec862</ex></ph>
@@ skipping 9697 matching lines @@
     </messages>
     <structures fallback_to_english="true">
       <!-- Make sure these stay in sync with the structures in generated_resources.grd. -->
       <structure name="IDD_CHROME_FRAME_FIND_DIALOG" file="cf_resources.rc" type="dialog" >
       </structure>
       <structure name="IDD_CHROME_FRAME_READY_PROMPT" file="cf_resources.rc" type="dialog" >
       </structure>
     </structures>
   </release>
 </grit>