Add chrome://slow for enabling performance tracing for feedback reports.

chrome/app/chromeos_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!-- ChromeOS-specific strings (included from generated_resources.grd).
      Everything in this file is wrapped in <if expr="pp_ifdef('chromeos')">. -->
 <grit-part>
   <message name="IDS_EMPTY_STRING" desc="Empty string, exist only to make code generic. No translation required.">
   </message>
   <!-- Idle logout dialog for retail mode -->
   <message name="IDS_IDLE_LOGOUT_TITLE" desc="Dialog title for the idle logout dialog. Used in retail mode only.">
     Are you still there?
   </message>
@@ skipping 1600 matching lines @@
   <message name="IDS_SIM_UNLOCK_NO_PUK_TRIES_LEFT_MESSAGE" desc="Message shown when there're not PUK tries left, right after last try was used and SIM card is now disabled.">
     You have entered the incorrect PIN Unlocking Key too many times. Your SIM card is permanently disabled.
   </message>
   <message name="IDS_SIM_UNLOCK_SIM_DISABLED_TITLE" desc="Title shown when there're not PUK tries left and SIM card is disabled.">
     SIM card disabled
   </message>
   <message name="IDS_SIM_UNLOCK_SIM_DISABLED_MESSAGE" desc="Message shown when there're not PUK tries left and SIM card is disabled.">
     This SIM card is disabled and cannot be used. Please contact your service provider for a replacement.
   </message>
 
+  <message name="IDS_SLOW_DISABLE" desc="The text of the button that disables performance collection for feedback reports">
+    Disable performance data collection
+  </message>
+  <message name="IDS_SLOW_ENABLE" desc="The text of the button that enables performance collection for feedback reports">
+    Enable performance data collection
+  </message>
+  <message name="IDS_SLOW_DESCRIPTION" desc="The description of the performance tracing feature for feedback reports.">
+    Enabling collection of performance data will help Google improve the system over time. No data is sent until you file a feedback report (Alt-Shift-I) and include performance data. You can return to this screen to disable collection at any time.
+  </message>
+  <message name="IDS_SLOW_WARNING" desc="The warning that informs users that enabling this can have a negative effect on their performance">
+    <ph name="BEGIN_BOLD">&lt;strong&gt;</ph>Note:<ph name="END_BOLD">&lt;/strong&gt;</ph> Only enable if you know what you are doing or if you have been asked to do so, as collection of data may reduce performance.
+  </message>
+
   <message name="IDS_EULA_BACK_BUTTON" desc="Back button shown on EULA screen.">
     Back
   </message>
   <message name="IDS_EULA_ACCEPT_AND_CONTINUE_BUTTON" desc="Accept button text below EULA terms of service">
     Accept and continue
   </message>
   <message name="IDS_EULA_SYSTEM_SECURITY_SETTING" desc="Link from the EULA wizard screen and title of the TPM info dialog">
     System security setting
   </message>
   <message name="IDS_EULA_SYSTEM_INSTALLATION_SETTINGS" desc="Link from the EULA wizard screen and title of the TPM and RLZ info dialog">
@@ skipping 2126 matching lines @@
     You are currently connected to the <ph name="NETWORK_TYPE">$1<ex>cellular</ex></ph> network.
   </message>
   <message name="IDS_UPGRADE_NETWORK_LIST_CELLULAR_ALLOWED" desc="Status label: for updates you need to connect to an Ethernet or Wi-Fi">
     To check for updates, please use Ethernet or Wi-Fi.
   </message>
   <message name="IDS_UPGRADE_NETWORK_LIST_CELLULAR_DISALLOWED" desc="Status label: for updates you need to connect to an Ethernet, mobile data or Wi-Fi">
     To check for updates, please use Ethernet, Wi-Fi or mobile data.
   </message>
 
 </grit-part>