Add viewing of error messages from Keystone upon self-update failure.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index 91b039ccd1498e06b6a6f46ecd5075e3adb1d46f..bf0f68ce9eb36199540b9d074347a65d89d3ce30 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -8104,6 +8104,12 @@ I don't think this site should be blocked!
         <message name="IDS_PROMOTE_AUTHENTICATION_PROMPT" desc="The prompt displayed in the authentication dialog when setting up automatic updates for all users.  The system will add a sentence asking for an administrator's name and password.  Mac-only.">
           <ph name="PRODUCT_NAME">$1<ex>Google Chrome</ex></ph> will set up automatic updates for all users of this computer.
         </message>
+        <message name="IDS_PROMOTE_PREFLIGHT_LAUNCH_ERROR" desc="Status label shown when an administrator user requested automatic updates for all users, but the OS failed to start the pre-flight process.  Mac-only.">
+          Automatic update setup failed. (Pre-flight process could not launch with error: <ph name="ERROR_NUMBER">$1<ex>1</ex></ph>)

[Mark Mentovai, 2016/03/24 18:06:38]

I think that we should simplify a little bit to limit the verbosity of the
parenthetical details and make things a little more accessible to ordinary
users. How about:

Failed to set up automatic updates for all users (preflight launch error %d)
Failed to set up automatic updates for all users (preflight execution error %d)

[Ryan Myers (chromium), 2016/03/24 19:57:28]

Done.

+        </message>
+        <message name="IDS_PROMOTE_PREFLIGHT_SCRIPT_ERROR" desc="Status label shown when an administrator user requested automatic updates for all users, but the pre-flight process reported an error.  Mac-only.">
+          Automatic update setup failed. (Pre-flight process exited with error: <ph name="ERROR_NUMBER">$1<ex>1</ex></ph>)
+        </message>
       </if>
 
       <!-- About Chrome View -->
@@ -8119,6 +8125,9 @@ I don't think this site should be blocked!
         <message name="IDS_UPGRADE_ERROR" desc="Status label: Error occurred during upgrade">
           Update failed (error: <ph name="ERROR_NUMBER">$1<ex>1</ex></ph>)
         </message>
+        <message name="IDS_UPGRADE_ERROR_DETAILS" desc="Status label optionally shown when an error occured during upgrade. The upgrade daemon may optionally send supplemental error messages; if they're available, we append them after this message in an HTML pre block.">
+          Error details:
+        </message>
       </if>
       <if expr="is_win or chromeos">
         <message name="IDS_UPGRADE_DISABLED_BY_POLICY" desc="Status label: Upgrades disabled by policy">