Use PageManager in About page

chrome/browser/browser_resources.grd

Index: chrome/browser/browser_resources.grd
diff --git a/chrome/browser/browser_resources.grd b/chrome/browser/browser_resources.grd
index e80ce8651780123f755a6b2568db3b4d2a242cbf..c1d0d10aebee6e002ff7026ef244d2358ed3a994 100644
--- a/chrome/browser/browser_resources.grd
+++ b/chrome/browser/browser_resources.grd
@@ -50,6 +50,9 @@
       <if expr="not is_android">
         <structure name="IDR_HELP_CSS" file="resources\help\help.css" flattenhtml="true" type="chrome_html" />
         <structure name="IDR_HELP_HTML" file="resources\help\help.html" flattenhtml="true" type="chrome_html" />
+        <structure name="IDR_HELP_CONTENT_CSS" file="resources\help\help_content.css" flattenhtml="true" type="chrome_html" />
+        <structure name="IDR_HELP_CONTENT_HTML" file="resources\help\help_content.html" flattenhtml="true" type="chrome_html" />
+        <structure name="IDR_HELP_PAGE_HTML" file="resources\help\help_page.html" flattenhtml="true" type="chrome_html" />
         <structure name="IDR_HELP_CHANNEL_CHANGE_PAGE_CSS" file="resources\help\channel_change_page.css" flattenhtml="true" type="chrome_html" />
         <structure name="IDR_HELP_CHANNEL_CHANGE_PAGE_HTML" file="resources\help\channel_change_page.html" flattenhtml="true" type="chrome_html" />
         <structure name="IDR_INCOGNITO_TAB_HTML" file="resources\ntp4\incognito_tab.html" flattenhtml="true" type="chrome_html" />
@@ -158,8 +161,7 @@
       <include name="IDR_HOTWORD_HELPER_MANIFEST" file="resources\hotword_helper\manifest.json" type="BINDATA" />
       <if expr="not is_android">
         <include name="IDR_HELP_JS" file="resources\help\help.js" flattenhtml="true" type="BINDATA" />
-        <include name="IDR_HELP_FOCUS_MANAGER_JS" file="resources\help\help_focus_manager.js" flattenhtml="true" type="BINDATA" />
-        <include name="IDR_HELP_BASE_PAGE_JS" file="resources\help\help_base_page.js" flattenhtml="true" type="BINDATA" />
+        <include name="IDR_HELP_PAGE_JS" file="resources\help\help_page.js" flattenhtml="true" type="BINDATA" />
         <include name="IDR_CHANNEL_CHANGE_PAGE_JS" file="resources\help\channel_change_page.js" flattenhtml="true" type="BINDATA" />
       </if>
       <include name="IDR_HISTORY_HTML" file="resources\history\history.html" flattenhtml="true" allowexternalscript="true" type="BINDATA" />